Well I don't know how I did it but I managed to make a washer that would fit And it fits perfectly (I can't get over how lucky I was) - after I managed to get the clip back into place (I spun the clip around a turn or 2 to make sure it was in and seated) I measured the end play and got around .005". No more slop - and there's no interference from the centrifugal advance that I can tell- it operates pretty smoothly by hand. I'll oil the mechanism (it was pretty dry when I took it apart) and should have the distributor together and back in the engine before the weekend.