I cannot believe it has taken me this long to come up with this. But, given that the standard for "new toy" (even from Hasbro) has been "put a new head on it" for the last few years, "Titan Wars" offers plenty of options. Hasbro can easily mould new faces (not even full heads) for the pilot figures.
If somebody is willing to paint existing figures, there are options.
Earthquake:
Hardhead's body and Skytreads's head. Paint in appropriate shades of red and brown.
Hurricane:
Use either Blurr or Brainstorm for the body. Use an appropriately moulded face. (Is it possible to swap the wind-vein on Blurr's head to another head?) My instinct would be to swap the head from Blurr on to Brainstorm. Maybe use Clobber's head? But, I would have to see the figures side by side to make a decision. Either way, paint in appropriate shades of silver/grey and maybe some blue.
Macabre:
Galvatron's body, maybe with Mindwipe's head? Paint in appropriate colours.
Considering that all of the above custom-characters were members of Squadron-X, and how Squadron-X died, the idea of them being headmasters is kind of funny.