Nice to see you here again!
Sounds like a fun project and engine-car combination. I always heard those Quantum Syncros were really an Audi Coupe Quattro underneath, but in VW station wagon clothing. Supposed to be great to drive. I knew a guy who had one and sold it and missed it afterwards. I imagine the 2.0 TD will be capable of similar performance to the stock nonturbo gasser, and much better mileage, no?
What's the motivation for the swap, just the benefit of turbodiesel power, or does the current gas engine have problems?
I think you will find the 2.0 TD very familiar to the D24T. Even all the same special tools for the crankshaft dampener and bolt, etc. Be fun to see your pictures for comparison to our engines. A lot of the parts are probably the same too, like the IP mounting bracket, cooling system parts, etc, right?
I bet that 2.2 gasser oil pan will bolt right onto the 2.0 TD (though maybe the TD needs a turbo drain return to the pan so that might be a problem to solve?). All accessory component mountings on the front of the engine should be the same too IIRC, with all the same bolt holes and bosses available, AND should also be the same as a 6-cylinder D24 or D24T. So that might be one easy solution to your idea of relocating the alternator to the passenger side, as it's already positioned there on a D24. A D24 or D24T alternator bracket and alternator would likely bolt right on. You might need to trim the bracket a little to remove the bearing housing for the engine driven rad fan (I assume the Audi/QSW don't use those?). Belt alignment might be a question if the Audi engines use a differently designed crankshaft harmonic balancer, I guess.
Look forward to seeing your updates. In case it gives any useful ideas, have you already seen this thread on a similar swap into an Audi 5000?
http://vwdiesel.net/forum/index.php/topic,25252.0.html
Slightly different car and he used the long stroke 2.4L nonturbo truck version of the 5cyl IDI for the engine in his and added a turbo to that, but same general idea, gas 5cyl to 5cyl TD. I ran across it accidentally looking for info on something else, but bookmarked it anyway, mainly just since the guy seemed to do an especially nice job with the conversion and put up some great photos. Fun reading and watching at least.