It's even possible to use a Hardley riser thats the same size as the origonal and use the origonal bars only difference would be the slightly different look of the aftermarket riser. Or like Benny said a washer would probably do it or a sleeve to bring it back to stock dia. if you have machine ability or know a machine shop to make them for you. Wouldn't cost much to have 2 sleeves turned.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!