Aisha

I have a 76 cutlass salon, the engine stamp says 396021F and the heads are 389395 part # 39410B so....is my motor a true 455? the heads are for a 425? I am confused I have been rebuilding this engine with tons of difficulty, i order parts for a 76 salon but then the parts do not fit, its been alot of trial and error because i cannot get certain parts, like timing belts/chain, I got a new harmonic balancer and a cam, but they don't seem to fit, so i am spending too much time measuring and finding parts, any advice