Diy Valve job
One thing to keep in mind...... a lot of the old equipment you see was bought and used daily at a machine shop for many years. Often, until it could no longer do its job satisfactorily ....... and it was removed from service.
To be able to do a “valve job”, you’ll need a valve grinder, seat grinder, stone holders, pilots, stone dresser.
The prices for that stuff new are absolutely insane, so used equipment that’s in really good shape can bring top dollar.
Whatever brand/model you’re looking at, make sure parts and supplies are still readily available for it.