1000rwhp isn't FT/LBS. The t56 is shown as Torque, not BHP. as discussed hundreds of times on here, it's torque what kills gearboxes/drive-train not BHP.
If the V160 is rated around 5/600ft/lbs (ish) and can take 1000bhp... Then a 700ft/lbs gearbox can also take 1000bhp which is the point i was making.
I only browsed the dyno section for a small while but it seems the highest power car in there has a Power figure - 821 hub HP Torque figure - 644 ftlbs which means the t56 would be suitable.
I don't get why you are trying to dismiss it, it's good for the supra market that there are alternatives. Allbeit, the T56 might not offer the types of ratios to make the drive decent enough for some people, but you can still get one for 4200quid that will handle 1000bhp and 700ft/lbs of torque.
If you want 1000ft/lbs it's 6286gbp.