Power limits for LA small blocks?

I hand some hands on a 408 back around '04. It made 580 n/a, and ran a 150hp plate on top. I know it went mid 10s without the plate. Heads were max ported Shady Dell RPMS. It can be done and doesn't take any pro magic. But it's expensive and the clock starts ticking the first dyno pull. He then built a big block car to go faster because the value (return on investment) was not there.