Sorry, matts37chev- I didn't see the first page of the thread before responding. The comment about the heads was more to add something on-topic instead of just flakking the guy for the street racing comment.
In any event, wild man- check out this build
to get an idea of what kind of flow (CNC ported AFR Magnum 315's w/2.25" x 1.88" valves milled to 110 cc chamber volume, being fed by a Vic Jr.) and how much cam duration (254º/260º @ 0.050") is needed to make 738 HP/666 TQ based on a Gen. VI 502 short-block (GMPP p/n 24502619)- an engine w/a lot larger bore diameter and a 4" stroke (giving less piston speed) than an engine based on a BBC 427 TD.
If you lower the power expectations by at least a hundred or so, things will become much more "doable", IMO.