Bebop, put a vacuum gauge on it and do some test driving. I'm going to bet you're only going to have 3-5 inches of vacuum unless you're coasting downhill. You're over-geared, and the carb is running in its "power" range all the time. A T-5 pulling 5th. gear against a 3.08 rear end is the equivalent of about a 2.10:1 gear. Either run the transmission in 4th. gear, or swap to 3.5-something axle ratio. You've got too much of a good thing, especially with those tall tires.
Jerry
