302 heads

One of the things you gain with the 302s, in addition to previous mentions, are hardened exhaust valve seats (for unleaded fuel).

The engines they came on had roller cams. If you look at an engine with the intake off, but the heads on, and see the lifter retainer in the block, it will probably have 302s if it is a 318/5.2 liter. To confirm, pull a valve cover. If the number cast into the head has 302 at the end, it is what you are looking for.