I've been searching high and low to answers to what is swapable on these engines. I know there has to be a difference in the K0, K1, K2 etc. But what head will interchange with which cylinders. So for example I have a K1 engine that has a head missing some fins, what are my options as far as what will work? Any head pre 76'? Also, are the jugs the same? Anyone want to show some knowledge on the differences. What's better, what works?....