There used to be rebuilt distributors available. Now, I'm not so sure. Some Oilite bronze, a lathe, and a couple of precision reamers would be needed to custom make a set of bushings. It's a fairly straightforward procedure for anyone with some basic machining skills, but I doubt that the bushings would be available off the shelf at the average neighborhood parts store. I've got a junk distributor or two stashed away, so I'll make a few measurements and try to post some dimensions for anyone interested in doing some fabricating.
The housing is a slip fit in the block, and the entire housing rotates with the vacuum advance. A little slop in the block isn't uncommon, and it doesn't have a great deal of influence on how the engine runs. Some people like to run a ground wire from the dizzy to the block, but if you do, use a piece of high-flex wire like a piece of a voltmeter test lead. Regular primary wire will fatigue and break due to the constant movement.
Jerry