One of my favourite headmasters from G1 was Highbrow, he just looked awesome with his dual guns and twin rotor helicopter. I am planning on doing (or requesting) a movie Highbrow done from Incinerator. Would the Omega Supreme headmaster fit well enough on Incinerator without looking too big? Would he be able to fit inside Incinerator's cockpit if it was hollowed out enough?
I have an Incinerator, but I'm not sure I've ever seen a Headmaster OS. Do you have a reference pic? Truth be told there really isn't a lot of room in the cockpit!
If you mean the Headmaster for Energon Omega Supreme, then yes it'd be waaaaay too big. The head's about an inch and a half wide and just about that tall and deep as well. The only thing that I think would be an appropriate size is maybe a G1 Headmaster Jr. On top of that, I don't think you CAN simply hollow out Incinerator's chest, because it's full of auto-transformation gears and mechanisms. All essential to his transformation. So for that area you'll basically have to completely rebuild the chest/cockpit.
Energon Omega's head is about the size of a fat Legends class figure, so way too big for Incinerator. He'd look like an SD figure with that on his shoulders. Besides being too big, it's also pretty rare. Energon Omega figures (regular and Sentinel versions) are quite pricey online, and if you find one second-hand, they're often missing their heads. I don't see a reason to use an Omega head instead of working with a smaller minicon as a base. Even so, incinerator's head is not very big... you'd probably have a hard time finding a TF figure the right size to make a headmaster for him. If you're thinking of expanding or "hollowing" the cockpit area (and it's true that would interfere with some of the automorphing gimmicks, though no great loss there), you might be able to make a small figure partially transform into the head, and have the rest of the body tuck inside the cockpit area so only the head portion sticks out... zmog
You could always try the Mega Blocks Neo-Shifter the mini guys like what im goin to do to make my Headmasters
The G1 OS wasn't a Headmaster of any sort. Additionally, his 'head' was little more than a diving mask with a gun on the back. I can't see how you'd ever use it for a Highbrow custom.