Hey man...I am in the middle of doing this exact thing, and I got a ZC that was in questionable condition also.
Anything on the block - 91 Civic Si (waterpump, rings, bearings, etc..)
Anything on the head - 89 Integra (valve seals, valve cover gasket, etc.)
Intake/Exhaust gasket - 89 Integra
Head gasket - 89 Integra!!!! <--- From experience, there is some question on various websites that say Prelude...use the Integra.
Timing belt - 88 Prelude 2.0 Si - this is the only Prelude part ;-)
Hope this helps dude.
Also - check out this website...the blue Civic is 91zc from this board and it hasn't failed me yet.
http://www.geocities.com/teampimports/