we took the cylender head off and found that the valves had gone bad so we replaced it with a brand new head valves and all. we put it back together and still wont run. we put a gauge on it and its getting 75psi. the piston wall looked good and no unsual wear just wondering if it could still be the piston and rings. also think maybe i didnt get the cam back in time right if anyone could help me with that 2

thanks