I have repaired too-loose balance holes about a half dozen times, using an updated version of the process described by Bill Spurlock in the May 1990 PTJ. Some of you old timers may recall this as the "Willis and David Snyder method". I revised it quite a lot because routers and router tables have changed, and I thought it needed to be safer, but it does work and it's a good repair. I haven't done it lately, but one of my colleagues used it last week. The process took him about ten hours, including having to make one new jig for the bandsaw (because that had been replaced since the last use). So, the big drawback is that it's expensive due to the time it takes, therefore it has limited utility. By the time you get done doing this, rebushing, new capstans, etc., a new keyset on the original frame makes good sense, unless there is a very strong reason for preserving the originals.
I can't think of a way to replace the .162" pins with .145", without replacing the balance rail or at least doing an insert.