It looks like Crazy Devy have come to the rescue with something I wasn't even aware I needed for my G1 Jetfire. A toon accurate (ish) head, articulated hands and gun.

http://tfsource.com/g1-skyfire-upgrade-kit/

I'm not sold on this idea at all. For me part of the charm of G1 Jetfire is the (lack of) face. While I can see a potential for articulation with their other offerings for Devastator or Omega Supreme, this just feels....unnecessary.