Get some of the thick adhesive used to stick posters to walls. Cut two small pieces and put them on the interior sides of Skids' head. The head will stay on and be able to turn properly.
That's about the easiest imaginable way to do it. When there's less of a size difference, you can use clear nail polish to tighten joints. There are several other ways of making that head stay on right. Reprolabels gives you the true kitbasher method, but ultimately whatever works, works. That last is the good advice Hobbyist Prime gave me not long ago.
I still seem to be the only one who likes reversing Alt Prime so as to make the windshield the chest like with G1 Ironhide. Check the threads and you'll find several different variations of varying difficulty.