If you are seeing a power difference and fuel curve not smooth or out of range the q-jet isn't up to par or fuel delivery inadequate for what you are doing.
I've been on the dyno with quite a few engines over the years, and have yet to get outrun by a Holley or anything else on a dual plane intake. On single plane intakes it takes at least a 1" spacer to run with a square flange carb as the huge secondary plates stick too far into the plenum areas when using a spread bore carburetor.....Cliff