The carpenter carbs are great.. We sell them at my work, and i have run one on my 40 for many a miles...
But.... Your best bang for your buck is a pair of CharlieNY carbs.. The Carpenter carbs are tuned for a single carburetor setup. If you are running two carbs on the same engine, I would send cores to Charlie, or he may be able to sell you two outright. He can fine tune them and set them up properly for your application assuming is it not a bone stock application.... Likely you'll come out cheaper as well...