The oldsmobile toronado GT 455 with 400hp and 510 ft/pounds of torque was a pretty stout engine.
People say the Mopar Hemi is what caused nascar to clamp down but it was the other manufacturers answers to the hemi that caused it.
The other manufacturers had engines being readied that were nothing short of unbelievable and this scared the nascar bosses.
Oldsmobile had at least 3 flavor of hemis.......some with 4 valve overhead cam....etc.
A few flavors of olds hemi and overhead cam engines.
Olds also liked turbos and remember they produced the first turbocharged production car.
Olds had deveolped.....
Aluminum 2 Valve 455, Aluminum DOHC 4 Valve 455, Aluminum 2 Valve Turbo 455, Iron, Aluminum 2 Valve 455 Hemi (W-45), and a Aluminum 4 valve 455 Hemi (OW-43).
Pontiac didn't want to be left out.
Ford actually produced cars powered by thier answer to the hemi.
Ford overhead cam 427 "cammer"
Ford Boss 429 hemi.
Small blocks were not ignored as chevy had experimented with the moser 4 valve small block.
The 4.6 is also a stout engine and we got 800hp out of one a couple of years ago on pump gas with a 3.4 whipple, cams, and mild head porting after we sourced a teksid block from a lincoln MKVIII.