Well, if you intend to keep this 2 pack in combined form, then the lack of a gun for Prime is a non-issue, as Prime did not use his gun in the movie when combined with Jetfire. To be movie accurate, just use the gun from Jetfire. You get the benefit of the nice paint job, chrome, and faceplate. It will look schweeet.
If you already have buster prime, then his lack of a faceplate is ideal for recreating the forest fight scene or for when he is not in combat.
Problem solved.
I actually like the head sculpt for buster prime.
Of course, my logic only works if you have unlimited funds available and can afford to buy whatever Has/Tak throws our way. That use to be me, but now that I have a newborn baby and my wife is not working, I have to be much more selective. *Sigh* I will just have to be content with my Hasbro versions of Prime and Jetfire.