For extra reference for anyone interested.
As ZSHO/Myself Have Mentioned in the past/this thread, the vacuum line for the brake booster uses a 3/8" hose, so if tapping that you need a T with 3/8" barbs to insert.
The TIP reference on the piping from the rear turbo to intercooler, uses 1/4" hose, so you would need a T with 1/4" barbs.
For the wastegate itself/ most wastegates/most BOVs they recommend 1/4" hose as well, and that is what the supplied nipples usually support. 6mm hose works as well.
f8tlSHO, my only concern with that location is that with the gate open, it may be too close to the gate and have a pressure drop causing the gate to chatter/oscillate between open and closed. But go ahead and test it out if it isn't too much trouble for ya, would definitely make line routing super easy.