Roots blower physical size

You can buy a blower drive kit for your engine, I assume your blower would be a 6-71 on a sbc chevy, you would need a drive kit for that blower.
I bought my full kit from good vibrations motorsports, they are good on prices.
They dont list a sbm on their web , but I am sure they can get a BDS drive kit.

http://www.goodvibesracing.com/Blower_Drive_Kits.htm