I wonder if it was a problem with the distributor grounding through the block? By removing the distributor and putting in the other it made connection now? I'm not that familiar with the MSD circuits, but the duraspark one needed a good ground to the block from the distributor. I've seen people throw parts at this for vehicles that sat for years and it was just corroded around the distributor... .
Electronics (with the exception of EPROMs) usually aren't effected by time - that said, the wires and terminals do corrode but technically that's a mechanical failure - Electrons always work.