Welcome to the world of customs! A junker seeker body should be a total cinch to track down... You could probably go with the Universe/Classics Acid Storm repros to help with the look...I mean, order yourself a sheet of repros for a G1 seeker, and also an Acid Storm, and then just mix and match...tie it all together with the paint job. Maybe think about hitting up the local hobby shop for a cheap 1/72 F-15? I would think that the scale would be close enough...hell the wings and tails might even look better than the original parts, and then you'd have all of those yummy leftover parts for your kitbash box. Are you completely set on leaving it G1? Since it's all taken apart, it wouldn't be terribly difficult to graft in a couple of ball joints and whatnot to add some poseability that the G1's lack... Either way, if you have experience with scale modeling, then all of this is totally within your grasp...I also got into customs after years and years of building model airplanes and it has been very rewarding for me personally. I'm looking forward to seeing how your fig turns out!
My plan is to make it G1 to go along with the other G1 seekers in my collection. I've yet to acquire Ramjet and Sunstorm, but with having Sunstorm, I figured this AcidStorm project should fit right in. As for making it articulated, I don't think I would know how to accomplish that. For now, being my first custom, I'll stick to just a basic repaint. I'll have a look at the classics AcidStorm sticker sheet, but I'd still prefer a G1 style sticker sheet. Like I said, I want this figure to blend in with my other G1 seeker's. I hadn't thought of using model airplane parts. But I might look into that for a future Masterpiece creation. It would be neat to have a Masterpiece of same size as G1 counterpart.
Seriously, get some JB Weld. It's plenty strong, and with it and the plastic part attached to the back, it should be strong enough to hold.