I don't believe the Aussie numbers. BS. Over 1400ftlbs of torque? Mbrannons are more reasonable
That said, I like the idea of a v6 turbo. I like the idea of one big one instead of two little ones, mainly due to plumbing constraints and room on the dside. There are only relatively minor mods needed to get the exhaust gas from the dside to the pside, starting at the current y pipe under the truck. You would need a custom pside exhaust mani, made out of stout stuff like a 3/8" flange and sch40 weld ells and a cross to support the turbo weight and heat loads. This also is convenient to the current airfilter and maf and tb setups, and doesn't have the brake booster and m/c in the way. The TT setup would leave you short on fuel on a 3.5, most likely, and the last thing you want on a turbo is a leanout.
You'd need some kind of custom f/i management system, but there are tons of them out there, from the cheapies like Megasquirt up to natl debt size units. You'd also need some lower compression pistons, or use the 24v motors and lower boost.
Turbo sizing wise, I'd like one that blows around 450-500cfm at 12psi, for the potential for 300+hp (it takes about 1.5cfm per hp generated, as a general rule of thumb). A mitsu 16ish would be about right, or even a 14 would also be almost big eoough.
The 24v motors would also present a greater fab challenge, in that the exhaust ports are oval instead of round, so if you go that route, why not use the 6g75 3.8 engine and get the extra 50 cubic inches and torque and power? At least use the 6g74 3.5.
You want to be conservative on turbo size, to keep the low end torque and minimize spoolup time. I'd want to do this on an a/t truck, to take advantage of the loose converter for spool up at lower rpms.
I'd shoot for a max statio compression ratio of 8.5:1 for a 12v, and 9:1 for a 24v, and a max boost of around 10-12psi with the best premium fuel you can buy. Forged pistons would be a really good idea. Stock cam is probably fine, unless there's a lot of valve overlap.
A three row radiator core will be a necessity. An intercooler probably will be, too.
