9A pistons will give you a CR of about 9:1 with a stock headgasket. The ABA uses larger wrist pins so you have to get the rods rebushed for the smaller 9A wrist pin.
You'll still need the rest of the conversion parts: int shaft, pump gear, block off plate, intermediate shaft gear, crank gear, distro, etc.
You also need a Passat 16v auto throttle body to get a TPS.
You can run a 16v head off of Motronic, by swapping the 4 window trigger wheel in the distro for the ABA's single window. I'm not sure how that should line up so you should defnitely examine your stock ABA distro and how the trigger wheel lines up at TDC for refrence.