[denisond3]

First, dont you live in a state where the car has to pass an emissions test including having specific things under the hood? If the VIN of the car doesnt match whats under the hood, would that make it fail the smog test?
I live in Virginia, where the smog test is based on either the smog requirements for the original motor, or for the new motor, whichever are more strict. They can fail you for having a turbo on a car whose VIN didnt reflect that - even if it passes the tailpipe test.
I have opened up and fiddled with several engines, some normally aspirated, some turbo-charged. In each case the turbo version had pistons with a lower compression ratio than a normally aspirated version; though I havent worked on a turboed VW engine yet.
Wouldnt a 2.0 liter engine be from a newer car? So you would need to adapt the car (which I think is an early Mk-II) to match the sensors/injection/fuel management needed by the engine (which might be a MK-III), or vice versa.