:..There is no (external) dimenional difference between the 302 and the 351 heads. All intakes,255,260,289,302,will bolt up to the 351 heads installed on a 302 block. On pre 77..351 heads there are 2 extra bolt holes on the the intake port surface (8) vs (6) the 302, but are of no importance when using a 302 intake manifold. The exhaust side is the same as the 302. The 5L valve covers bolt up but need to provisioned for PVC hookup if used.