I'm not sure how the WP rating from the old BEAM equipment and the new IMPCO equipment are related?

The IMPCO reg and carb are designed to work together.

The BEAM system is 250lbs WP 0.19 PSI water column.
The IMPCO system is 312lbs WP and 2 inches WC


I took off the cover on the primer button side.
The diaphragm looked -as new- I looked carefully and closely
and saw no holes or rips or cracks.

Put it back on and tried to start the engine.
I noticed propane smell and looked everything over carefully.
Gas is escaping from the vent screen.
A slow steady silent flow of gas.
The primer button seems to have a lot of resistance when pushed. It was that way before.

So apparently sitting around for 25 years never being used has still had ill effects on the rubber products in the unit.
This was never installed on anything, it is as new.

I am ordering a rebuild kit right now.