stock stroke, high compression, good heads, and a big cam would get you there I'd think.

or you can cheat, drop a 440 stroke crank in there from your choice of stroker sources, (aftermarket that's already made for the 383/400 mains) and turn the 383 into a 426, 431, or 438 depending on how much you have to bore the cylinders. That, combined with compression, head flow, and cam, will get you 450-500 hp that is VERY streetable.

my 383 stroker was making over 500 lbs of torque at 3,000 rpm where the dyno started measuring, and it stayed at a nice flat 500 lbs through the RPM range, peaking at 535 at 3800, and made a peak of 505 hp. that's with the above combo--440 stroke, flat top pistons, eddy heads, comp's xe-275-hl hydraulic cam.