[Pete]

I have never tried building a supercharged flathead because they are not allowed in vintage circle track racing so there is no market.
However, I have wrenched on several fairly good ones over the years.
For street use with a 3-71, a 600 cfm 4 barrel carb would be ideal. I would use a Holley because they are simple to street tune. They are very simple to adapt to a GMC blower.

Here is a pic of a 36 coupe with a 3-71 and 2 Stromberg 48's back in the mid 50's. It turned 110 in the low 12's consistently.
404A cam. The guy drove it to work during the week.