Regulator
What about mounting the regulator right at the carb on a bracket? They sell brackets for all brands of regulators that mount off the carb studs for 4150 and 4500 style carbs. Just run your main fuel hose along the passenger fender and make a 180 degree turn back toward the carb. Then 2 short #6 lines out of regulator to the carb bowls.
I have never had any problems doing it this way, running 4 seconds in 1/8 mile. Vibration doesn't appear to effect it as far as I can tell.