452 heads

There is enough flow there to potentially get you to 500 HP.

Are they fully ported? No.

cc the heads and mill them .0042" for every cc you want to reduce the combustion chamber size. If they were 88cc they would need to be milled .017", 90cc, mill them .025". For every .010" you mill off the combustion chamber surface you should mill the intake surface .0123" so the intake manifold will line up.

I think you could run the 91 octane, @ 9.7:1 compression, with that cam you have listed.

We used a set of 452 heads, flowing 295 cfm, to get 620 HP from a 451/400, 91 octane, 9.5:1 compression, 950 cfm 4150, M1 single plane, solid roller 254/260 @ .050, .582"/.588" lift.

I have successfully run 11.9:1 compression with iron open chamber heads, 280/288 @ .050 and 91 octane.