Thanks for your query. That's what I was thinking too. Before looking
into the timing, I thought I'd better make a final attempt at the
distributor. I noticed that the resistance between the primary and
secondary coil was off by 3k ohms. I'd dismissed it earlier, but
thought to test the variance anyway. The new coil was within the range
of 12-18k ohms. With it installed, the engined fired right up. Just 3k
ohms! Can you believe it?

Thanks again