About 30-50 miles at up to 30mph is the usual spec. for transmisions with internal oil pumps like our TR7. I know of a Ford Truck with internal oil pump that had it's transmission wrecked by towing. The owners manual said don't do it. I had Yellow TCT towed by tow truck (8 miles at under 30 mph) where it's trap fits under the front wheels and lifts them up.
Towing with a chain is asking for trouble with the slackening and jerking of chain. Like when I helped my neighbour try to move his boat balanced on tire on cab and rear of box (his idea not mine). Just ended up scratching his new Toyota 4x4 truck up. (I was able to buff most of it out except for dents and chips).
TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra