Restorations of antiques can be a problem in this area if you don't have or know someone has the needed machining tools. That when our skills as machinist can come play as boring, installing a shop made bushing, and then reaming so the shafts fit. The main trick is keep the initial boring centered as most times the wear is going to be lopsided.
Sometimes you get lucky and a ready made bushing works with only a slight re-sizing; just depends shaft sizes and carburetor casting.
