The Borg Warner T5 is a great transmission as well. They have a .68 5th gear which gives you a great rpm reduction equivalent to a TKO-500. I had a T5 in my '90 mustang before switching to a TKO. It stood up to my 347 stroker motor and a super charger to boot for about 6 months until I blew the crap out of it.
They are only rated at 250ft/lbs but obviously I had way more than that as you do as well.
As long as you take care of it and be careful with the 2-3 upshift when power shifting, it'll last you a good long time.


Richard
Tech Support