The Unior brand of bike tools includes reamer/taps to re-thread 9/16" pedal holes to, I think, 5/8 and matching inserts to get back to the proper 9/16". Both right and left hand reamer/taps are available with RH and LH inserts to match. Niagara used to sell this stuff and I've seen it on Amazon and Ebay as well, but don't know about current availability. My recollection is that the tools and inserts were a bit pricey, but perhaps a shop has the tools and the knowledge to do it at a reasonable price.