Have you done a compression test since it quit?

I'm not familiar with the distributor swap, is the advance curve in the electronic distributor the same as the breaker point one you replaced?

If it advances more, or faster, you could have gotten into detonation (hear it rattle any?).

My concern being, with the distributor change being the only stated difference that if you got into detonation it could have damaged the pistons and or rings, allowing extra pressure into the crankcase.

As others mentioned, extra pressure in the crankcase will push, potentially, copious amounts of oil past felt seals.

I hope that's not it, but it's all I could think of that could trace to a distributor change; since from what you say it isn't leaking from the distributor.