Hi guys'''I have a 1995 pick up 350 chevy engine casting # 14093638 with heads casting #14102191 center bolt valve cover can I install early 70s heads on this block? happens that I bought .200 pop up pistons and dont fit with the original heads. the another alternative is to change the pistons for flat top ones I have an crane energizer 278 hyd flat tappet cam and performer edelbrock manifold any suggestion will be grateful. thanks

Those heads are for an 1987 and up 350. I think they are 64cc. With out doing the math, even with 76cc heads I think your compression ratio will be too high with them pistons and small crane cam.
To answer your question...sure you can use 70's heads on that block. I would rather see a set of flat tops and maybe Vortec or a good aluminum after market 64cc head.

Is the engine still in the truck or is this an engine you're building for a project? We took a '93 TBI engine, dropped a pair of RHS vortecs on it with a ZZ4 take-out cam and GM's TBI intake and a 454 throttle body. It'll run a hole in the wind, made a wimpy truck into a friggin' tire shredder. I'm with bigjimzlll, vortecs and flat tops are the way to fly, IMHO.