How large ate the holes?
I'm a little OCD when it comes to this sort of crap.
I use a Forstner bit too drill a perfectly round hole and buy Dowling in Ash to epoxy in to the holes. You can then grind and reglass the effected area and drill new holes.
This of course relies on the test of the wood being in usable condition.
GT
I didn't measure how much out of round they are but I'd have to guess u could probably fit a 3/8 in bolt in it now on the inside of the stringer. Whoever installed the kit before just put big washers on the outside of stringers so I'll be replacing that with a piece of 2 in flat stock down the stringer to give it more area to clamp to. Where would I beable to find ash dowels an what kind of epoxy would u recommend?