Roots blower physical size

I am still a long way from actually buying the blower. I am concentrating on the rest of the engine first. But, from what I can figure, I will be trying for an 8 to 10 lb boost limit. I am looking at a 7.5 to 1 static compression ratio. I am also looking at a water/meth injection setup to be on the safe side.
I have seen a couple of 6V-71 setups for sale and they seem to be cheaper than a 6-71 setup. I haven't figured out why yet, but I will.

Jack
>Jack, I bought mine, nos. for $200. They look "different", and not too many, know about them(demand)."Dyers" sells them rebuilt, ateam.