The 4788 is a downleg booster carb.
I run 3.91's with 27-1/2" tall tires and a 9-1/2" Dynamic converter.

If you guys think I won't gain anything over the the 830, then I can find somewhere else to spend the money. I just figured it would go a little faster with the bigger carb, and the street HP version should offer good street manners (??).