I think that the towing capacity of the V8 Toyota equals the towing capacity of a modern C10 or F100 and may exceed it.
According to this
http://www.hemmings.com/hmn/stories/...rs_guide1.html a stock second series shortbed V8 truck should weigh right at 3217 lbs so your truck with the big block but minus some pieces should be close to the same. That is fairly light by today's standards.
A 2000/2006 V8 Tundra has a 7500 towing capacity.