I'm in the process of putting a late 80's ZX600 Kawasaki swingarm on my CB750 race bike. It's a boxed section aluminum unit that was originally designed for a mono-shock set up. However, it takes the same size pivot bolt up front and it actually slightly narrower than the stock CB750 unit. So all you have to do is to have some spacers made up to center it in the frame. You need to cut off the mono-shock mounts and have some alloy lugs welded to the arm to hold the twin shocks, but all in all it's a relatively easy conversion. The Kawi arm is about 2" longer than the stock 750 arm though, so you'll need a longer chain. Not sure what the stock axle diameter is on the Kawasaki swing arm, but the one that I have has already been modified to accept the larger rear axle from a '85 GSXR750 18" cast wheel.
Pics coming at some point.
Tracy
Yes show us what you do. I've seen other bike's aluminum SA grafted on CB750s and for the sake of the collective data bank, I'd like to know which ones fit up and what's involved in each conversion, spacers, mods, brake rods, etc.
And benefits, perceived or actual, like lighter, stronger, fit wider tire, etc.
The store bought ones sure are trick, though.