To me this is a no brainer! Get the rpm heads. Heads are not by any means too big.
Fwiw I had a 383 12.5 to 1 with ported 915s and a 590 cam.
It liked rpm but one day at the track a wise man told me he bet I would run the same numbers shifting at 6k.
He was correct. With rpm heads I think it’s as good a combo as you’re going to get with what you have.
Good luck 👍
With 9.75 to 1 I don’t think your cam is too big but I would not go any bigger. If you stay with 452 and 9 to 1 I would agree it’s too large.