Royster asked this before, but nothing was conclusive.
Can an NC29 rear wheel be fitted??

bump!!

Fitted... to what?

I can tell you that with spacers a 29 wheel fits a CB-1 in terms of physically fits and the brake works, but that the chain run will be off. I suspect the wheel alignment will therefore equally be off line. And that it is a swine / not possible to try and get right, so I ended up just changing the whole rear end on my CB. The two swingarms are the same width at the engine, but I think the extra width for the wider wheel is added on the right.

Complicated to explain, but basically an nc29 wheel won't fit in a cb-1, or it will, but it won't line up right.

I think you would have more luck with a cbr600f2 wheel, I believe that fits a cb-1, so should fit your 400sf too?