OK. Running the numbers and it looks like it's as I suspected.

I just kept thinking "4th low" would be lower than "3rd hi".

Axle is 8.1/6.1

Trans:

1st 7.05
2nd 3.58
3rd 1.71
4th 1.0

Rear tires are 900-20 (I think?) Not sure what the OD is.
Engine is a 350ci from a '90 police package Caprice w/Q-jet carb.

I'm not sure what top speed will be. That little sbc likes to rev and has a pretty wide torque band.
I wonder what the mileage will be... 8-10 mpg?