I don't understand the need for more information on the boiler to give basic maintenance advice that applies to ANY cast iron sectional boiler.

1. It's not a great idea to add a corrosion inhibitor. Basically, when you add new water to your heating system, that new water contains dissolved oxygen and hardness ions. Most of the dissolved oxygen comes out of solution when the water is heated, and that which doesn't forms rust in the iron sections of the heating system, notably the boiler and the associated iron piping. The hardness ions in the water (mostly Ca++ and Mg++) form scale on the hottest surfaces of the heating system, which will be right inside the boiler itself.
If you don't replace the water in your heating system (and you should try to avoid doing that), the oxygen will be driven out of solution, and what's left will form rust, and the hardness ions will form scale. Thereafter, your circulating water will be both oxygen depleted and ionically dead, and that's exactly what you want and need to prevent corrosion or scale build-up in the heating system. So, in my humble opinion, it's far better to just operate your heating system with old water rather than use a corrosion inhibitor. At only about 60 to 65 years old, your boiler isn't very old, and if you take good care of it, it'll last longer than grandma. There's lots of cast iron sectional boilers still going strong after 100 years.
Also, if you have to drain your heating system down to do a repair or whatever, collect the water you drain out in 5 gallon pails. Then, when the repair is completed, carry those pails up to the top floor of your house, and siphon that old water back in to the highest elevation air vent in your heating system. Then, just add a bit more city water to bring the pressure back up to 12 psig or slightly better. There should be a pressure gauge on your boiler by which to do that.
To do this quickly and easily, buy a 1/8" NPT nipple, a 1/8 inch ball valve and a coin air vent, and screw those into the air vent on the highest elevation radiator in your house (or one of 'em). Close the ball valve, replace the air vent with a 1/8" NPT X 1/4" hose barb fitting, get a siphon going and push the siphon hose onto the hose barb fitting. Now, open the ball valve, and the siphon will fill the heating system of our house with the old water (which won't contain any dissolved oxygen or hardness ions).
A plumber won't do that because you're paying $90 per hour for his time. But, he'll do it in his own house.

2. You do need to clean your burner trays and the space between the sections of your boiler periodically. Rust will form between the boiler sections and fall onto the burner trays, blocking off some holes, and collect on the horizontal fins on the boiler sections, thereby interfering with heat transfer. You can buy special brushes to clean the spaces between the boiler segments, but I've always just used a "carboy cleaning brush" that you can buy at any wine & beer making store. If you clean your boiler like that once every 10 years, you'll have a clean boiler.

3. Depending on the kind of circulating pump you have, you may be required to oil the motor bearings (as well as the bearing assembly) at the start of every heating system. Typically, you put 1/8 fluid ounce of oil in each of the motor bearing oiling caps, and 1/4 fluid ounce of oil in the bearing assembly at the start of each heating system. Newer circulating pumps will have permanently lubricated bronze bushings in the motor, and so you only have to put oil in the bearing assembly at the start of each heating season. It's a good idea to keep a spare spring coupler handy. That's the part that goes between the motor shaft and the end of the shaft the impeller turns on. If that breaks, you've got no circulation of water, and that means no heat regardless of whether the boiler is working or not. Better than a spring coupler is a Spiroflex coupler because they'll almost never break:

4. Newer hot water heating systems will allow for the expansion of water as it's heated with a bladder tank. Older systems used something called a "cushion tank", which is nothing more than an empty tank that gets flooded with water so that about half the tank is full of trapped air. It's that air cushion that allows for expansion of the water into the cushion tank as the water expands when it's heated. If you have a cushion tank, it's a real good idea to install a sight glass on your tank so you can check the water level in it. But, as sight glasses can be notorious for air leakage out of them, on my cushion tank on my old heating system, I installed a ball valve on each port provided for the sight glass, and installed the sight glass between the ball valves. That way, during normal operation I kept the ball valves closed and only opened them momentarily to check the water level. That way, any air or water leakage past the packings around the sight glass won't affect the boiler operation.

5. Best to keep a spare thermocouple on hand as well. That's the doo-hicky that generates a small voltage from the temperature of the pilot light flame, and that voltage is used to keep the "safety" magnetic valve open inside your gas valve. (Post again if you want to know how gas valves work.)

6. I've familiar with the Honeywell 8043 series zone valves. About the only maintenance they typically require is a shot of a light oil like WD-40 if they stop operating. In the 21 Honeywell 8043C zone valves in my building over 25 years, I don't think I replaced more than a dozen motors, and only one sector gear. Depending on the kind of zone valves you have, you can make inquiries as to whether the manufacturer makes a kit to allow you to replace the actuator or "head" on the valve without draining the heating system. If they're Honeywell zone valves, then your in luck cuz Honeywell does.

7. And, on my old boiler, whenever I cleaned off any rust in maintaining the system, I'd spray that cleaned area with WD-40. As that oil dried on the metal, it formed an impermeable film between the metal and the surrounding atmosphere, thereby keeping the rust from reforming in those areas.

8. Since your city water pressure will typically be about 50 psig, but your heating system will normally operate at about 12 to 15 psig, you will have a Pressure Reducing Valve (commonly abbreviated "PRV") on the water supply line to your boiler. Take note that the PRV will normally have a brass or stainless steel filtration screen inside it. Eventually, that screen gets clogged up with crap in the water, and needs to be cleaned. Most people that notice that their heating system is operating at less than 12 psig will start monkeying with the pressure setting on their PRV, only to find out that doing that doesn't change the pressure of the water in their heating system. Once they discover that the filtration screen in their PRV was clogged up, then they have to play around with the pressure setting screw until they get the PRV set back the way it was. If you notice a low pressure on your boiler's pressure gauge, clean the filtration screen inside your PRV before you start changing the pressure setting on the PRV. That way you'll only have one thing to do, not two.

That's about all I can think of right now.