I have to say if I had a 360 short block with kb flat tops in it I would run what I had. I don't think I would shoot for 550 + HP. I would build the best combo I could that would have good life expectancy. I think you could get 450 hp that would live in a street strip car. Any more than that and you are going to run into drivability issues like hard to start in cold or wet weather, overheating in traffic, fouling plugs etc. High horsepower numbers are great on the track but seldom work well on the street.