The 500whp # is extremely dependant on where you rev the motor. If you keep it under 6K, then it should last longer. If you are running a blower and the crank is getting yanked on every time you get on it, that is another issue as well. Plenty of guys who ran a stock bottom end with loads of spray, but didn't rev to the moon who kept them together for awhile. Personally, I would build a motor with a good block if I was going for that hp #, but if that isn't an option just be smart about the build.
I killed my 302 when it was probably 350 flywheel because I revved it to the limiter all of the time and spun a bearing, then the crank took a break. At 500 wheel it's a crap shoot honestly.