The 8 1/4 axles will take some abuse. The 9 1/4 is a better choice though.

I'd suggest using a light weight trailer. A tow dolly might even be a better choice. The tow dollies I've used did not have brakes, so stopping it may be an issue.

On the gear ratio, a 3.55 may be just fine. Many years ago, I had a Fury with a 318, 904, and a 2.76 axle. One time I towed a full size pick-up truck with it using a tow bar. It did OK on level ground. Once, I had to stop on a semi-steep hill due to a red light. When the light turned green, I pushed on the gas pedal... and the car sat still. I floored the pedal and after several seconds, the car finally moved. I made a point of NOT stopping on hills the rest of that trip!
(Towing that much weight with that car was a bad idea...I did not know about manufacturer's tow ratings back then!)