Biggest ballache you will have is getting the cossie box to physically mate up to the gearbox / clutch i should think.

Physcally mounting the engine that way round isnt a problem at all, same as in the mondeo cossie FWD i just bought recently for example.

Obivously that means custom downpipe etc though!

Isnt the audi 4wd gear based on a longitudinal engine layout?