Spool vs SG

I bought a brand new clutch type sure grip in ebay for $330.00. I know that is still more than a spool, but on the street a spool will be hard on tires and axles. It will work though, as I know many people that run them on the street. As far as the 4.56 gears for a 741, I don't think any one ever made them. Maybe a 4.10 if you can find one, but the highest numerical I have seen is 3.91 for a 741.