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.

I think that other 50 horse will be there without a lot of chasing.
Say that because of a similar type build i had
416, W5 heads, 11.5 compression, 260/266 flat tappet, 597/623 lift. “ standard” ringpack.
Brett Miller modified Victor W2 intake. 1 7/8 TTI W5 headers
In a 3350 pound A body that combo ran 10.30’s @ 129 ish.
Broke the cast crank and tore up the shortblock late that season
The next season i took the same heads, headers, intake, carb etc on top of a 422
Difference was 043 ringpack, 273/280@ 50 roller that was 699/672, and 13.3 compression. Roller wasnt a spring killer, i drove that everywhere.... springs were 240/590. More aggressive profile later on made more steam on that combo
Changed nothing else on the car, just the shortblock
9.85@ 135.............. not sure what that difference was, but its more than 50 horse.
This is a car i raced year in , year out for a long time
I think the TF heads would show less difference than above, because they aren't as “ big” but i bet they would show 70% or so of that difference

Edit.... to take it a step further, the W5’s went 10.30’s that one season before i broke the motor. As i posted above
They replaced an eddie top end. Moderate porting from Hensley. Excellerator intake, tti step headers, same everything else including the 260/266 cam
That combo i ran for a few years. 10.74@ 124.60 best

Guess the moral of the above story is a good head shines much more with stuff under it to use it
W5’s on that 416 were limited by that camshaft, that was fine on the eddies.
The trick flow heads should be able to get a typical A body bracket car in the 9’s fairly easily
My stuff has always been heavy because i am 300+ and like steel everything, no glass.