A 600 hp pump gas stroker engine is pretty easy to build these days. You shouldn't have any trouble hitting those goals with a 10:1 compression 505 if you use Trick Flow 240 heads and pick the right cam. If it was my engine I'd use a hyd roller with 240 duration and probably go with a Performer RPM intake. I'd highly recommend using EFI such as a Holley Sniper kit. The shop I work with builds about 10 of those engines a year. With a baby cam they'll make 550 hp but if the owner is willing to turn the cam up a notch or two then they'll knock down 600 hp. The trick is to use the Sniper kit and the Hyperspark distributor so the computer controls the ignition timing. That allows you to tune the engine so it will run super smooth with the performance cam.
Thats about the same answer i got from Hughes when i ordered my cam for a 505 stroker.