are the v6 tdi's mounted front to back?
You are correct. the V6 TDI is mounted north/south. They share no parts with the golf.
The only way that you could ever install this engine in a mk2 golf would be to cut the complete front end off the passat and weld it onto the golf.
A more practical, but still very technical, swap would be a PD150 engine and trans from a mk4 golf into the mk2 golf. At least the engine would be mounted in the proper direction, if nothing else.