There is a Gilson Wheel on Ebay right now for $75 + shipping. It looks like it's in good condition. There were a set of forks on there the other day. I also have an original speaker tail light. If you're interested, just let me know via PM.
Your bike is missing a lot of parts, but the frame looks like it's in nice shape (aside from the bars). Without having the badges on the bike, it would be difficult to know whether it was a two speed or a TC set up. If you wanted to go two-speed, you could order the Comet set-up from BlackWidowMotorsports.net for about $150 shipped. You'll need the longer jackshaft though.
I have a nearly complete Gilson that I'd be happy to take some pictures of if you need some for reference. Mine is only missing the exhaust. Everything else is there