Concerning the PFHC01 head, the actual face itself (excluding hair) has identical topology for both games. The only difference in TSL is that they tweaked the positions of some of the verts slightly, giving it a slightly shorter nose and chin, and less full cheeks. The UV map has some very minor changes as well. Part of that may have been to fix issues with the original K1 map, but they also added a mole to the upper lip on one side (so they needed to break those polys out to their own texture space). With the hair, it's basically the same, the TSL version just has a different fringe and the dangly bits at the sides. So for that head, you really don't need any mesh alterations at all, just a texture tweak.
For the PMHC04 head, there's no obvious direct descendent of the mullet man, but in terms of facial structure TSL's PMHH01 is the closest. Hair-wise it's the closest as well, so it may well have been a derivation of the PMHC04 mesh. If you weren't too picky about the hair, you could do a texture tweak on this one as well to bring it more in-line with the K1 head.
Basically what it boils down to is that model changes are problematic, so asking for radical model changes like replacing all the hair is probably not going to get you any takers. Texture tweaks are easy though, so if you can live with that you are far more likely to get what you want.
Edit: Tried to upload a a quick and dirty edit for you to try out, but I can't get any hosting sites to work properly. Blergh. Here's a pic. It still needs some tweaking of the colours and such to better match the K1 head, but if you'd like a copy then PM me an email address and I'll pass it along.
http://i374.photobucket.com/albums/oo185/DarthParametric/th_PFHC01_Retexure.jpg) (
http://i374.photobucket.com/albums/oo185/DarthParametric/PFHC01_Retexure.jpg)