I had a CNC ported head 451 in a '65 Barracuda with 3.91's and yeah, anything past 1/4 throttle was dangerous as I could not get a good tire back there without tubbing or going to a soft track tire. Too much for that chassis for me on the street: youll find it hard in turns, very light on the gas. Id go with the lower gears if i did it again. The Dart chassis is a much better candidate than mine.