Valves are the same size, i pulled these heads off a 273. But the intake bolts are different from stock, unless you plan on running a different intake manifold.
my engine is a 65 273 block , it had 675 heads on it previously and then replaced with 920s. also has a ld340 intake small ports. why does everyone prefer the 302s if they are so much like the 920s? are the 302s closed chamber?