Its cost vs gain
a reliable 450 crank HP out of a 304/355 is a 10 grand exercise.
I have a a box worth of stout bottom end bits sitting in a box (H-beams, good bearings and flat tops etc) but
700 bucks for a roller cam, 500 on roller lifters, 600 on rocker arms, 1000 on a bit of headwork, 900 for an intake manifold, 800, on headers....and it might crack 400hp and run a 13.
Or I can buy a hypergear highflow and a fuel sysyem for the 33 and with some tweaking of the rear end, run 11s