I don't know if the B20E distributor will actually work on a carb'd car. It has the contact system for the injectors in the lower part which you don't need and this also means a there is a hole in the side for the electrical plug for this.
Sounds as if your distributor just needs some tlc and a good clean up to make it more reliable. It can also be converted back to points or maybe to a Pertronix system if the Crane trigger stuff is broken and parts are unavailable. Being UK I've no knowledge of this system beyond seeing it mentioned now and then.
A full mechanical, no vacuum, one from a B18b could be a good choice if you can find a decent one.