Do the TKO you'll pay for it by not having to keep replacing and rebuilding a T5 of any flavor.
Don't waste your money on a T5 in any form. Everybody talks about super T5's from various vendors and how they are supposed to be so good and hold up under all sorts of driving. The trouble is they usually don't own one. You never hear from anyone that has a super T5 that they have driven for 10,000-20,000 miles or more and not had problems. The T5’s problem of the case spreading so the gears engage only at the gear tooth tips is still present. That causes them to fail anyway, even with the stronger gear material.
I have a Tremec 3550, the little brother to the TKO, that I have driven for more than 10 years. It still shifts fast, and smooth, I never lift off the throttle to shift and it never complains or gives me problems. As long as you run the correct lubricant and the right amount of it, they are almost bulletproof.
With your engine and rear axle gears you will need a lower numerical set of gear ratios for best performance.
See
http://www.tremec.com/menu.php?m=103 for more information