Here's another perspective on numerically low rear axles ratios. My Stovebolt is a restored '36 Chevy pickup. I converted its rear axle ratio from 4.11 to 3.55 using 1950 Chevy car gears in a '37 Chevy car rear axle. The '36 has a bone stock original 207 cubic inch engine that easily pulls the 3.55 gears, including on a long 11% grade near my home with the transmission in 2nd gear on that hill. Your V8 is much more powerful.
My other toy is a '32 Ford roadster street rod. It has a very mild 350 engine (Crane cam with 218*/230* duration @ 0.050" specifications, Edelbrock 9:1 aluminum heads, Performer intake manifold, Performer 600 cfm carb, block hugger headers), 200 4R trans with 0.67 OD ratio and a 3.80 rear gear. In OD the effective gear ratio is 2.55 and the roadster engine pulls that ratio easily at any speed over about 50 MPH, although it did not pull the 3.40 rear gear ratio I initially tried in OD. Cruising along at highway speed in OD now the roadster gets about 19-20 MPG and mashing down on the accelerator triggers a downshift, or even a double downshift that puts the engine in its torque sweet spot that really pushes us back in the seat. In 15 years and 23,000 miles of driving that roadster I've never regretted the highway friendly gears.
So those numerically low gear ratios are definitely feasible in light vehicles like our "Cowboy Cadillac" Stovebolts.
