My dad installed the bushings in the throttle plate on my carb as he was retired and it gave him something to do,what he did was get the od of the shaft and went to a bearing company and found bushings that had the same id as the shaft and was small enough to work in the base plate and found a drill bit that was a fracion smaller than the bushing and set the base plate in the drill press and drilled the base plate. The reason he got a bushing a little bigger than the hole drilled is so the bushing would have to be slightly pressed in so they would stay in and not turn with the throttle shaft and it worked good and I never had any problems with the carb again. Your 66 will have a point ignition and I used the electronic system from a mid 70s big block and it made a big difference in starting. grin