Before you tear into it get it running and do a compression test! The base engine is just a stock marinized 350 parts should not be an issue, you may still have the old style Chris Craft manifolds and risers with the wye valves they may be hard to find. The wye valves are the fittings on the inside of the risers with the T-ed hose going to them, they can easily be done away going to new exhaust. They were a pain to begin with, never made much sense why they had them. The Tstat will help a lot with the condensation, one thing you should do is to pull the valve covers and inspect the valve springs, it is fairly common for them to rust from the condensation. If they are rusted fair chance one or more will break, if they are rusted you have options depending on your compression test! If the compression if off pull the heads and have them done with new springs, if the compression is good you can change the springs using air pressure to hold the valves in place. You will need the fork type spring compressor, pretty easy stuff I have done quite a few. Phil
No matter what your beliefs are "GOD BLESS AMERICA"
Fully retired marine tech near 60 years in the biz.