Wanted: 261 Chevrolet engine

[motto]

A few years ago I was helping a friend in another city build up a 216 from a bare block. For some reason the gasket set he had did not contain the rear main seal halves so we went to an old parts supplier he knew of to buy them.
We told the elderly gentleman behind the counter we needed the rear main seal for a 216 Chev and away he went.
When he returned he had a single stick of rope seal instead of the two we required. When we told him we needed two of them he was completely flummoxed and said that he had only ever sold them one at a time for that was all anyone ever wanted.
It would seem that it had been common practice for a long time to only replace the lower section.
Maybe that is sufficient to reduce the leakage to an acceptable amount?

David