Well I have been using a Daytona Universal carburetor on one of my 216s for over two years. It is the best carburetor I have used on one of these engines. It gives me twice the mileage of my professionally rebuilt W1 and it was brand new and I believe made in the USA!
What kind of fuel economy are you getting?
My stock, non-rebuilt 216 with Carter YF gets 13-14mpg on highway/city combo driving.