carb question

Many variables apply to your choice. You mentioned more performance but, do you drive the car regularly or does it sit for long periods where the fuel can evaporate completely from the bowls? Carters (excluding the Thermo Quad) are more forgiving than Holleys for this abuse. Holleys have the power valve diaphragm and accelerator pump diaphragms that get crispy after a few cycles of this. They do make green ones for alcohol that last a little better. The thermoquad has main well seal rings that are a rubber or Buna N compound that will shrink and harden and also leak after a few cycles of evaporation. There are many tuning tricks for carters in the "Yellow Book" that are worth while but Holleys are much easier to tune and get parts for and usuallly out perform the carter in my experience. The 3310 is a great platform to work with.