What's interesting about the Dambest carb is the emulsion well design and booster outlet. From what I could tell from the design is that his approach is to increase mixture quality with a threaded main well and then distribution and homogenization with booster outlet design. Might be worth a try.
Id personally go for the 850 and play with booster hole sizing and number to see what your engine likes. The real difference might be in the Tslot.
Maybe try Mark Whitener for a carb. At the least he'll get you the T-slot right as well as the emulsion package then you can play around with booster hole sizing and numbers to see what your engine really likes.