I finally got around to fitting the billet steel adapters for 340mm discs. Both of my 18x9 wheels fit with plenty of spoke clearance.
Had to bend the RS3 dust shield out a bit more near the bottom, since the carriers attach on the opposite side as the 370mm audi ones.
My bolts all got mixed up since VBT did the recall, waiting on them to confirm the torque specs on the bag I had floating around.
Had a hell of a time fitting the pads even with the thinner 15mm spec (CT1001, not CT1001A, in the case of these). I think this is probably just due to my aftermarket pistons, or I need a better piston retraction tool.