I can understand the want for a better rear shock, but I haven't really heard much complaint of the B6's steel swingarm flexing.
I'm pretty sure the wheels are shared with other Suzukis - maybe in different colors, but an aftermarket wheel shouldn't be a big deal, as long as you don't mind spending the $$$. I know Bill Blade put aftermarket wheels on his B12 and didn't have trouble finding them, but at ~$3000 (for the ones he bought), I can think of better things to spend my money on... but then he'd already dropped in a 1216 kit and smoothbores, so he had that end covered, too.