You don't mention how it ran from a dead stop before you changed carbs. If you dropped bottom end power after you changed the carb, chances are that is the first place you should look.

If it's the 4 hole spacer that that cuts down to little half moon openings before it goes into the intake, go pull your Q Jet out of the trash and replace it with the spacer, or bite the bullet now and buy a square flange intake. If the engine is slugish chances are its starving for fuel/air because of the restriction in the primaries.

If you want to continue to try the combination, you might want to go with step rods a couple of steps richer and see if that helps at all, it's only a band-aid however.