I don't think the carb is your problem either.
You should be happy with a 347 making 431 RWHP. Very good numbers.
As for the gear, a 4.10 should be plenty of gear. You don't want to run out of gear at the top-end of the track.
Oh, and ~510 FWHP will destroy the T5 on your first or second pass - or before you get to the track.
E