Rocs, I have a 16" rear Lester for the CB500/550. It appears to be unused. Doesn't look to have ever had bearings or the retainer ring in it. I also have a 19" front Yamaha wheel. Looks very, very close to the Lester. Many people wouldn't be able to tell the difference. I've seen people use them on the SOHC4, but I don't know what it takes to make that happen.
I even have a low mileage 16" rear tire that came off my Dad's bike when he switch to an 18" rear wheel. Shipping would probably be brutal, but I'll make you a helluva deal on them.