[MKS427]

I run a 3.08, same size tires (they're shorter than the 15"s, which increases gearing), TKO 600 w/.64OD and 572hp 585tq. If I could get a 2.90-2.80 rear gear (not available for the 8.8 Ford), I would and switch to the .82 OD. With the 2.87 first gear it tops out around 45mph and NT-01s aren't sticky enough to put it to the pavement. The 2.32 first gear in the Toploader seems better suited for these cars, but lacks an OD. Currently, I'm at 2000 rpm @ 75 mph in fifth. You would be about 2550 at 75 mph and 2730 at 80 mph. According to my calculator, you are 3150 at 80, currently. I know 3.00 is available for the 9", which would get you to 2660 rpm at 80 mph.
ALSO, you can change the OD gear without buying a new transmission. Contact Dederichs Motorsports for parts. He is in Fort Worth. 682 365-5555 .64 OD would get you to 2450 @ 80. Tremec has just released their TKX transmission, it is dimensionally identical to the TKO600, but is gasketed and has better syncros. Dederichs can set you up with that too and you could sell the old TKO. I believe a .73 OD is available with TKO 500 0r 600 gear sets.