Replacing 302 heads with magnum heads

The 340 exhaust manifolds do fit but I had to double gasket them to get them to seal. The magnums are more expensive in that you either have to order them with the la intake pattern or get a Eddie intake. Yoe also need to get the correct pushrods, lifters and I had the studs replaced with 7/16ths ones so I can run any spring pressure I want. You'll need around 120#s on the seat and 320 #s on the open valve if you use a roller cam. Mine are good for .510" lift and have some bowl work. They flow better then most la heads. Mine came in at 68cc's out of the box. You'll have to hunt for a source for the 62cc's. The question is, do you really need to use them on your build, the 302's with some work will do fine and you'll save a lot of work and money. One other thing, I'd get a custom grind cam, maybe send them a good core and tell them what your plans are. Good luck, the 318 is a great motor built right.