Before you go spending the money on that I'd start with the known working 650 AFB you already own or one of my 750's. You can always improve later, but I bet you will be quite surprised how well that AFB will work on a properly designed engine. My 440 ran it's best (so far) with a 750 AFB on a stock iron intake!
So are you suggesting I use my stock intake and carb or just the carb?