I think the Mk4 has IFS, so it can be fitted but it's a bit of work. The engine will fit easily with the right mounts, and so will the box as long as you have the crossmember and cut a new hole in the floor for the gearleaver if it's an MT75 5 speed. You also need the prop shaft.
Well that won't be too difficult to fit, the floor would need cutting for the MT75 though, and I think you will need to grind off the old gearbox mounts as the MT fits using a crossmember.