I thought it might be of interest to those who lurk here to know that, as I was eating lunch today, I flipped-on the TV set and caught a several-part series of Hot Rod Garage. The topic was a '70-something 454 chibrolet engine they took apart and then dolled up with after market parts including heads, a roller cam, headers etc.
I did the same sort of thing several years ago, starting with a '64 PI (C4) solid lifter block.
When all was complete, they managed to wring about 470+ horsepower out of it. My 390 combo produced about 30 more horsepower on the first full pull after break-in. And it got better from there.
The purpose of both exercises was to build a worthwhile street motor.
KS