Heads have no 2da. As long as they are in the correct naming style you should be gold.
That said I think CEP actually added a parts_head.2da file for scripting purposes... been awhile since I've looked in on that. If you aren't using CEP though don't worry about it.
Far as I know the upper limit on all body parts, including heads, is 255 (256-1, accounting for 0). So you should be able to number them up to that.
In case you aren't aware (not that I know much either) though heads 50-100 won't be accessible in the toolset. I have no idea why Bioware made this so, but players can still access them if you use a body tailor or head changing script of some kind.
P.S. This screwed me up the first time I tried it so I pass the warning on in hopes of making the world a better place. When you rename heads, and most body parts, you need to edit the PLT file name to match the new number. You also have to edit the MDL file itself to use the changed texture number. EG. Changing pfh0_head001 to pfh0_head100, change both mdl and plt to head100, then edit the mdl file in notepad, change all refrences to pfh0_head001 to pfh0_head100. Don't just change the 001 to 100. Plenty of numbers in that file that can do all sorts of weird things if changed on accident.
You can also use the NWN Model Renamer
http://neverwinterva...n-model-renamer
One of the great little tools. Don't try changing the PLT names with this though... causes problems.
