I've done this same job MANY times. I thought 0.030" over was the biggest oversize piston available.
My Kohler engines were on Gravely commercial power units. They used the K301S engine. It had a special end on the crankshaft. When the bore got more than 0.030 over, I'd buy a Kohler engine used from anything and swap cranks shafts. These often had to be rebored. Not that big a deal if you were swapping cranks anyway.