Since I never drag raced at a track, the best I can give you is my 64 Barracuda, it was the same power to weight as a 68 383 Road Runner. Both 4 speed both 3.23 gears. I remember being surprised I could not run him down. That was with the sorry 1850 Holley, Offenhouser intake, 64-65 273 heads and a TRW TP-141 solid cam. When I switched to 1.88 intake J heads 340 intake, TQ, 340 cam and 340 valve springs it was much faster than the Holley/Offenhouser intake, not even in the same league. Always have to laugh at "no replacement for displacement". I disproved that nonsense all the time. Of course my friend raced Super Stock when you had to run stock unported heads. By then I knew what I was doing and stopped reading magazine BS. A better adage is there is "no replacement for good machine work, combination, and flow".