Looks awesome so far. Might I suggest, check out the CB1100F.net forum, we do a lot of rear-sets over there, plenty of different ways of doing it, and on our forum they're all shown clearly with lots of tutorial type build threads. Might I suggest something off a CBR? Do you want to retain the two-up seating? If so, maybe the stock pegs off one of the 'F bikes could work, as they've got the passenger pegs integrated. It can be a problem not to move the passenger pegs back at the same time, as their feet will keep knocking your feet and vice-versa while shifting and braking, etc. So a plate set like on the 'F incorporates both, plus the brake master cylinder, spaced correctly, only needing to be cut/drilled etc to adapt to your frame. Or adapt the frame to them, or both. All you'd need is a couple of threaded bosses welded on, maybe even drill a couple of holes in the frame? If not, there's a great method on the SOHC4 forum where mountain bike steering stems are used as pipe clamps to mount stuff on the frame tubes without permanent modification. The swing-arm pivot on the GL is a bit different than on the 'F, but I'm sure that the peg plates could be shifted aft a little bit and still work great. Me, I'm partial to the old school steel tube triangles, and I'd like to weld up a set onto my 'F to give it that clean, classic look. But for the time being, I've changed the stock forward position plates to a rear-set type. Hey, on another note, companies like Tarrozzi and Raask, maybe even Dunstall, made rear-sets for these bikes when they were new. Not cheap, but they're a bolt-on modification.
I love what you've done. Have you checked out the Naked Wings forum? Randakk's cycle shak? Lots of cool cafe style 'wings over there! I'd sure love to see more of them here, and I'll be checking in on your project as well. Is that the 18" front wheel? Those are very much in demand for the CB750/900/1100F bikes. They make the 'wing look so much more sporty, and the 'F as well. I've got this wire 'wing wheel for my '82 750, but I am sticking an 18" rim on it, so it's not ready for the bike yet. Yours is waaay ahead of mine, so far as completion is concerned. I love a well done cafe, especially a 'wing cafe. Just don't deck it out in the checkers and pirate flags, please?
-Sigh.