I'm around 600/600 and it's a blast to drive on the street. Let a buddy drive it and he couldn't believe how docile it is until you hit the loud pedal. I am really impressed with my True Trac rear as well. Even with tire spin it just keeps moving forward.
Now an old school small block with a flat tappet cam may be a little peaky over 500hp. I'd go roller cam or more cubes.