If you plan on running a qtr. i think you're going to need 4.10's certainly no more than 4.30's, blower motors have a tendency to come on strong on the bottom end, unlike a turbo motor, The boost is up immediately, around 3,000 rpm. I'm going with 4.30's in my Anglia but donot intend to run anything but 1/8 mi.
JMO
Zip.