906 vs 452 heads on 440

Ah. ok. In terms of as-cast as Jim's info shows - they are pretty much the same. Personally I prefer porting the 346/452s but to each their own. Any head can be tweaked by a high quality performance valve job and if it was me I'd put exhaust seats and larger valves in it regardless. So the intake seats would be re-cut anyway. I don't think you can go wrong either way.