I am assuming engine since he says "runs good, but has...". Although he doesn't specify what kind of "water leak" it is. Could be anything from a bad radiator hose to a cracked head. I am guessing it is closer to the latter although I'm sure whatever it is it is an "easy fix".
I attempted to contact the gentleman a few weeks ago and left my phone number. He never contacted me. I have 1986 Buick T-Type parts car to use if I needed any extra parts.
Hmmm sounds like you want to do a 2.door t-top conversion Bently1 With suspension work and roof rack removal it would be super cool. I'm guessing head gasket or worse.