In answer to being unsure how much the drivetrain could handle, the 6-speed drivetrain is out of the STI so it is definately capable of handling a good amount of power. How much exactly I don't know, but never the less, it can take a lot even stock. The details that you have been given on this build are pretty good if it's a just a rumor, not fact. The upgraded drivetrain and the choice of using the "disco potato" turbos, which are known for comparatively large power in a small housing, are things that would most likely HAVE to be used in order to build a TT SVX. Otherwise, go TT porsche motor swap (which I would kill to see).
Megasquirt is another option for engine management and their tech line is great for helping you build one of their computers.
Lastly, Welcome Twinboosted. I also have a VG30DETT but I am currently in the middle of putting it into my 1990 240SX.
Can't wait for that beast to be running. I may have to ask you some questions about the deleted exhaust systems, get some advice.