273 correct heads?

Kecmp said
the heads on my 1965, 273 has a casting number of 2465315-2 with hydraulic lifters. Are these the correct heads or are they from a 318 engine?

Those are 64-65 273 heads...

You may want to consider swapping to a 66 and later 273/318 head with the more common intake bolt angle and size... Then you would have a better choice of intake manifolds to upgrade to...