This is what is looks like when I start a new project, a floor full of parts:
The spare C105 frame:
My first bit of chopping. I had to shorten the headstock, and attach the wider bearing cups for the Yamaha forks:
The front forks fit. I think these came from a Yamaha YG. The truth is, they came from a dumpster over at Clint's, a gentleman in Hamilton City that lets me rummage through his parts.
This is just a mockup with some flat bar, but it proves the concept:
The big 1/2" bolt is tacked to the flat bar, and essentially acts like s sliding pillar. The lower spring is about 75# and takes care of bump travel. the upper spring is about 40# and takes car of droop. I used a spare 1/2" heim joint as the steady perch, which threads into a long sleeve nut welded to the frame.
The front tire is way too small, but you get the idea on the overall proportions. And yes, I plan on some sort of handlebars that extend up a bit. Not monkey bars, but maybe something that extends up about 6-8", with a real narrow width.