It'd be a lot easier to answer your question if you were explaining what you're trying to do - how much HP are you going to make?
From what I've seen/read, the stock TT auto trans itself will fail long before the TC itself does, usually between 400-500hp depending on the tires you're running and the way you drive.
By the time you're making that much power, and need a built Toyota auto, you'll also be installing an upgraded higher stall TC at the same time.
I can't recall seeing a Supra that was set up with a 500+ HP single setup, built trans, and stock stall. I'm also not intimately familiar with all the ways that various upgraded TC's are reinforced to handle high HP.
I do know that Titan's new stall converters have been getting a lot of praise, and a lot of folks are going from PI converters to Titans because 700+hp power levels don't start blowing through the Titan converter on the big end the same way it does on the PI unit.
Hope that helps.