Boss 302 cars were high performance cars with special engines. The Boss 302 head is slightly different from Cleveland heads in that it has provisions for water to go through the intake manifold like a regular sbf engine, but requires special head gaskets, intake gaskets, intake manifolds, etc. They are low production cars, and engine parts are relatively hard to find for restoration projects. I have a NOS Boss block that I have owned for over 42 years just waiting on a car to put it in. I have a NOS intake manifold that is hard to find, etc. Boss heads are not just cleveland parts. The '69 Boss 302 heads had 2.230" intake valve, and the '70 was reduced to 2.190" intake valve. Joe-JDC