According to fura-2 :
I hear what you're saying, but maybe I could just bang 'em back to
near-flat or cupped, depending on what looks best. I've got an arbor
press -- you think that would give me enough force, esp. if I used a
pipe extension on the handle?

Frankly, I doubt it. (Aside from the problem of maintaining
proper alignment.) What tonnage rating of arbor press? I would not try
a 1" or larger punch with my 3-ton arbor press -- pipe extension or no.

I remember the effort I had to put onto a 1/2" drive ratchet
when punching steel relay rack bottoms with a ball-bearing screw and
grease on the threads.

And I remember breaking the drive screw on one of the 1/2"
punches. And that is one *tough* screw.

Greenlee sells a hydraulic drive for the bigger punches.

And the amount of force needed on the handles of a Weldon hand
punch with 1/4" punch and die installed -- if you are working on steel
makes me think that you would need more force for a larger punch than an
arbor press is capable of providing.

Although -- if your metal is thin enough and/or soft enough, and
the holes are small enough, *maybe* you can get away with it. Make sure
that the die is firmly mounted on the anvil, and that the punch does not
wiggle far enough to the sides to contact the edges of the die.

Maybe make a fixture to hold the two parts with guide rods and
springs to pull the punch back out of the die and the sheet of metal
stock which you are using. (But this is pretty close to what you need
for a punch and die which will give you flat workpieces.)

Good Luck,
DoN.
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