Sort of metal related...

Came across a couple of 75# CO2 tanks used in a Kidde fire
extinguisher setup. They currently have Kidde I-Valves installed.
The fortunate(?) part is that the tanks are still full, and hence the
dilemma.

I would like to adapt the I-Valve to something more "normal" for now,
and then once the tank is empty put on a CGA-580 valve. The second
part is easy, but I am not having much luck finding out what even
interfaces to the I-Valve and then any method to adapt it to a
regulator.

I don't want to spend a lot, as it is just to salvage the gas that is
in the tank. So the solution has to be pretty cheap (~$20-30), or
there is little net gain to just venting the tanks and then swapping
the valve and refilling.

Anyone here familiar with the I-valve and where to find fittings for
it?

JW