Hey Nick, figuring a 30% loss in the drivetrain, you'll need 585 at the flywheel to make 450 at the wheels. While it's not impossible to make 585 with a naturally-aspirated small block, it sure will take a shoebox full of Franklins. And you'd have to use so much static compression ratio and so much cam and so much converter that the beast wouldn't be any fun at all to drive on the street. If I were trying to do it, I think I'd start off with an 8.0:1 383 short block, some 195cc AFR or TFS 23 degree heads and a blower of some kind puffing 8 to 10 lbs of boost into the motor. This would make a "driver" motor that you could operate on pump gas.
Here are the details of a build at Airflow Research showing the parts used and the results...
690 HP
383ci - Blown with 671 Weiand Supercharger
AFR 195 Competition Package
7.8:1 static compression ratio
2 Holley 650 Double Pumpers
MSD Billet Distributor 32° Timing
Xtreme Energy Hyd Roller Comp Cams
230°/236° .544-.555 lift 114 Lobe Center
1 3/4 Headers
93 Octane Pump Gas
690 times .7 equals 483, so that should put you where you want to be. Call up Airflow Research and discuss it with them....
http://www.airflowresearch.com/index.php