[MKS427]

431", 850 will make big power at cost of bottom end, vice versa for a 780. Big cams, my experience, do not pull enough vacuum below 1800 rpm for the carb to work well, below 1800. Have you checked into accel pumps? I went through all of this, spent a bunch of money and time, scrapped the carb and went to EFI. BETTER, streetability with a big cam. Recently, change to an EFI cam, bottom end, 1000-1400 greatly improved. GOOD LUCK