[DonC]

For what it's worth I went with the 0.82 fifth on the newer TKO 600 with the 2.87 first gear ratio and 3.07 rear end pushing 17" rims. Very pleased with the driveability of the setup.
Cruising at 70 puts the RPM's at about 2200.
Spent a lot of time with the gear calculators before I finalized on the setup with several criteria driving the decision.
First of all I have the car to drive it. 14000 miles in two relatively short (3 1/2 month or so) driving seasons here in the northwest.
Went with the 17" rims for the greater selection of tires available vs the 15".
3.07 rear as a happy medium between acceleration and cruising.
My big block is a very mild build with 450 HP and 475 lb/ft of torque. It allows me to poop around at 35 mph in 4th all day long if I need to and have a very comfortable ride.
If I was more interested in straight line acceleration I'd probably go with a rear end in the 3.27 or 3.31 range but for me this combination works very well.
For straight line I can't really say since I've never gotten around to stripping the car but at the London Cobra Show I was consistantly at 96 mph on the Main Street Burnouts which, as I understand it, was a generous 1/8th mile.
DonC