How secure does it need to be? Do you really need a different lock, or could you just have a locksmith make a key for the original one?

Locksmiths love old lock sets. You can get that re keyed or get a new inset piece and continue to use the knob and face plate.
Linda c

Thanks. DH took it to the locksmith this afternoon and I think we've got it worked out. We are not able to reuse all of the doors - for various reasons - but we will try to reuse most of the hardware.