I’ve seen several different approaches to the oil seal mod, which all result in success. The tough part is keeping the new larger hole for the seal in concentric with the original hole. We were probably overly pedantic about how TT and I did mine and Bob’s, but I wanted to make sure it was going to work right. We made the ring in the lathe to hold the seal so it fit into the depression for the original. The excess material was removed with a hole saw. Then the ring brazed in for a perfect fit.
(Nice website btw, Dave. I like your sensible mods.)