Although I may not have the resources to make it happen, there are those who have done successful Audi Quattro / VW chassis drivetrain swaps. I happened to find this rather lengthy and informative thread over in the S2 Forums. Thanks to this particularly well documented build, it is clear that a very large amount of work is needed to make a project of this scope come together the right way, and not some hacked together jigsaw puzzle conversion.
As the owner says, it's pretty much an Audi S2 with a Mk2 GTI shell and steering column. Everything else has been swapped over and upgraded. That, my friends, is a lot of work. Not the uprights, not the suspension, not the steering, not the brakes, not the axles. None of those things are VW based anymore. The radiator and related parts have all been sent to the rear, fed by NACA ducts located on the sides and top of the car. It's all very well done, it's clean, and it looks like, well, a proper race car. I mentioned to my buddy Jason that to do a 5-cylinder swap in the Scirocco we'd probably have an easier time of things building a tube frame and then fitting a Scirocco shaped shell around it. This car pretty much prooves that theory 100%.
What we can see this adds up to is a very strong performer on the road. (uptight-job-having NSFW type language from the passenger in this video, FYI)
Damn impressive. I don't have much else to add except, this makes me even more inclined to figure out how to make it work...or at least something like it. I have a bunch of 4-cylinder stuff already lined up for Scirocco Madness, so I doubt I'll be going down this road though. Logic when thinking about project cars? I must be getting old. Tons more pictures and info available on the thread don't forget!