Awesome...The front end bolted right back up?
A 2008 TT should be straight forward to just swap the whole 3.6 into.
You have the correct Accelerator Pedal, you don't have a PS pump, the cruise control should work with the 3.6, the cooling setup should be basically the same as the 3.6 Passat.
Unless your TT is manual. No 3.6 came in manual except the Porsche SUV, so most ECMs don't have the clutch pedal input.
Honestly, just shove the whole 3.6 in, here's one in my MK4.
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