the deal is i have a used 85 truck engine thats going in my k5. i plan on re-gasketing it and doing an rv cam/lifters/t-chain/oil pump replacement before i install it. current mileage is unknown, but it does run well, and has had valve seals installed at some point. for $200 i can get some 487x heads that are fresh with 1.94 valves. should i waste the money, or just run whats on it. current heads should be 76cc, and the others 64? thats going to bring the compression up. but maybe too much? or maybe run a little bigger cam with some overlap to tame the compression? the k5 is 5500lbs, 465/doubler/4.88s. 43" tires edit- i realize there are way better heads out there, its just that they are cheap and rebuilt.