Several guys in our owners club run old Chryslers, without too much issue that I know of. Assuming the block is sound and you've got compression
in each cylinder... they probably don't take much work.
I understand there are several options for better carburetion and timing, and the cooling
system needs some care (new elbows -- and risers, if you've got 'em -- no more than every 5 years) but the latter seems to be a common deal with gas engines, anyway.
Can't believe there's not a bunch of motorheads in your area who could do service
for you. Aside from installation
(in a boat), flame arrestors, and the cooling
system... I think there's not much "marine" required...