Welcome to the forum!
Most commercially rebuilt Q-jets are pretty bad, if not junk- mismatched castings, a "universal" approach to the build and cheap parts. That said I would strongly recommend the purchase and thorough study of Cliff's book to get a real feel for what a Q-jet really should be.
Also, consider building an unmolested carburetor. Cliff can supply you with quality parts and a baseline for how the carb should be built.
My suggestion- return the rebuilt and try the route I suggested. You will be very happy with the results.