MK4 Golf to Jetta front end if common. Personally I hate, ugly imo. It's either you love it or you hate it.
You would need a Jetta hood, fenders, bumper, lights and grill. If you source the parts from a junkyard youd be able to do it pretty cheap.
MK5 front end I haven't seen before. Probably been done before but with a lot of hackery. There are some companies out there that sell MK4.5 bumpers, Bumpers that look like from the MK5 but fit on the MK4 but personally I don't like it either.
If you want a MK5 front end you should've just gone and bought a MK5 imo