You had all the good motors, which are out of production now mostly due to the unconstitutional executive regulators in DC.
I don’t know enough about Chevy’s new small block motors (such as the LS7 427 in some of the recent Corvettes rated at over 500 horses, or the LT1 376 in the current Camaro SS which is now up to 455 horses) to really say anything about them.
You can still get many of these engines thru GM’s Performance Catalog.