Alternator and Dizzy is, but cam wont be, the early cam only has one worm drive that fits oil pump and dizzy, where as the later cam has two worm drives. you can use the later cam in the early engine as the other worm drive becomes redundant. Sometimes the engine mount placing can be different between early and late, but thats more of an issue when going to an A15. Be aware that the mounts that bolt to the block can also have different profiles so don't throw anything away.