I tried the 3.08 in my 54, 1956 235, single Holley/Weber, w/Fentons with a .72 T5 and a 28.5" tall tire. It was great around town as a 4 speed but you had to be running 65-70 to get it into the torque curve and it was very flat....no pickup and the engine labored. I went with a 88 Camaro with a 3.42 and built my 1960 dual Carter/Weber, Fentons, engine up for low end grunt.
Around town you can use 1-4 and drop down to 35-40 in 4th.....slide into 5th at 50-55 and you're good to go. Don't have any real lugging.... down to 45 mph in 5th. No downshift necessary to run back up. She's happiest at 65-70 at 1900-2000 rpm's in 5th. I'm working on getting my fuel mileage up to 21+ and have no doubt that I can better that with a 65 mph cruise.
With the 3.42 setup at 65 mph cruise, she's just purring along....plenty of throttle left up to 80 but up there the wind noise and aero package (brick) make for some white knuckle driving....but it's there!!!! All under 3000 rpms.
I considered popping in a .86 T5 but with the 4.03 1st gear you'd be wound up pretty tight at 10-15 mph. I see no need to stress a 4 main engine that by design, was set up for low end torque. Cutting down tire height gives you about 100 rpms per increment and the stock 235 works well at 1600-2300 rpms.
I just couldn't see any sense in having an OD transmission that wouldn't give you a chance to cruise in 5th. IMHO I would recommend a 3.42 as the lowest number (tallest) ratio....a 3.55 or 3.73 if you live in an area with long hills or plan on pulling a load. Hope this helps!
Dave
