ditto to what jason & busdaddy said.
i just ran into this problem about a week ago with my 64 with 1600dp, alternator, and 34pict3 carb.
the accelerator pump linkage was hitting the alt. the previous owner had ground down the alt a bit but not enough, so i put the carb in place, marked where the clearance issue was, and carefully ground down the alt with my die grinder.
like jason said, it doesnt take much, but it works like a charm.
good luck.