You cannot simply convert LUP, CUP and PSI one to the other, let alone base CUP thrust which is what the English doubles used in proof. I nearly drove myself crazy looking for definitive data.

As far as selling these conversions, the old English doubles had their max loading in bullet weight and charge stamped on the actions. So stamp a very conservative loading as max and if somebody buys it later and exceeds this then it is their look out. Most people for example know about 45-70 in spingfields as opposed to Ruger No1's and the very different loadings for each.

At the end of the day I would have to take the build it, enjoy it, and get a relative to throw it in a river when you die, if you are worried view, because in the final event how much money are wa talking about, the cost of a good set of car tyres a nice holiday, not fortunes.

Regards