Agree with Dan. Current .740 is nothing to worry about—just an over bored 12. Heck, I have some totally original Parker’s with bores at or even greater than that. But wall thickness is everything. I see it still has original 2 1/2” chambers—that’s good. But what is wall thickness in front of forcing cone? And on down the bore? A lot of guns will pass proof with very thin barrels on down towards muzzle but be aware that they dent very easily and there’s not much metal remaining to repair.

When an old man dies a library burns to the ground. (Old African proverb)