I made half washers. I measured the differences and sanded down washers to the right size. I then tack welded them to the original thick dished washers and ground everything pretty. They work great, the only downside is that I have to keep track of which washer goes where. Never try tightening them things down without making up for the difference, I have seen a cracked manifold due to this procedure. It was able to make up the washers in about an hour. Much cheaper than taking it to a machine shop.