Thanks for the generous props folks - I feel lucky to have been in the right place at the right time, and to have been able to strike a deal with PetePO. My wife is very understaning
As for the spring dimensions, I didn't take any measurements but I certainly will when I get a chance. However, I'd estimate the piston is about 1.75" in diameter, with the spring being slightly less, maybe 1.5". The spring wire diameter looked to be about 1/4". I'd like to get a PF I can put a pressure gauge on to see what the pressure generated during the shot are - will a typical faema E61 PF fit, or do I need an official Conti PF?
I'll tweak the pressure down to 1.1 or so, it seems like a good place to start. That's what the Cimbali I had was running at.