Trick Flow small block heads
600 maybe but after that, you are going to spend way more than it's worth to get more power out of that architecture.
Imo, that's the make or break number.
If they won’t make an honest 600hp(ootb) on a “suitable” bracket race type short block, then they’re not as good as they really should be.
I think they’d do it though.
I’ve made 589hp from RPM’s that weren’t anything too special.
We did a “hot street” 410 a few years ago.
10.5cr, tweaked RPM’s, Victor, qft 850, small/slow solid roller 251/259-108, .600/.600.
I wasn’t the one who tested it, and it sure looks like there was power left on the table with the tune up...... but it made 524tq/538hp as it was.
The a/f ratio was still way rich(11’s) and I feel like there was probably another 10-15hp in it with the carb sorted out better.