long tube or short tube primaries

I'm building a new set of 1 7/8" primary headers and i'm using borla collector mufflers. I don't know if I build the primary as long as possible or as short as possible. I've got a set of zoomies that are 1 7/8" also and I'm just looking to quiet it down for the street.

sbc 355 11-1 cr Littlefield 871 @ 15 lbs psi dart 2.08 mallory super mag injected alcohol