the 24v 2.8 vr6 comes in a mk4
so it would prob be engine, box, loom, clocks, shafts? keys? for a working conversion (maybe fuel pumps)
then brakes, wheels to accom 312mm brakes arbs.
by which time you could have bought one with the cash you would have spent - no point in putting the 12v engine in a mk4 IMO (also IMO never build what you can buy)