You don't need a solid roller for 500HP,, If your going racing ONLY, sure it's a given, but uyou wouldn't be limiting yourself to 500HP then now would you

. If your driving it, you'll be well off with a nice hydraulic roller and meet your goal. 5.7" or 6" Eagle ESP stroker H-beam rods work nice in a 383. Makes for more rod to cam clearance. SRP pistons are a fine piece and a good buy,,, and available in many dome / flat / dish configurations to make compression targets.
Heads are where the power is made. All the compression in the world, huge cams, nothing will make up for a poor flowing head (except boost). I am very partial to the AFR line. The 210's work really well on a 383, the 220's and 227's require a offset shaft rocker system to get geometry 'right'. Don't believe that 'works with standard Chevy valvetrain" claim on the AFR site. 'Works' and 'works RIGHT' are two different things. IMO a 383 ought to be treated as a 400 and nothing less than a WELL flowing head in the 210-215cc range (220 if it's track only or more cubes). Get lift up into the peak flow of the head (.600 for street is easy enough on a good set of hydraulic roller springs with the heavy 2.08" intakes) If using a hydraulic roller, the AFR Hydra-rev kit will keep the valve train in check up to 6200-6500rpm. Really the hydra-rev kit is more to keep the lifter toss / valve bounce in check more than extending the rpm range. On the street a RPM intake with some porting, or on the track a SuperVictor works well with a carb in the 800-850cfm range.
That's just one opinion,, lots of ways to skin this cat and have it shooting 500HP out it's butt at will