Hi Craig,
That serial number would be the 1952-1982 format, which breaks down as Engine No. 927, 5/1 model, built in 1952.
Given you say it was commissioned in the 1960s, I wonder if there's a digit missing? e.g. 9275112 (which would make it a 1962 engine).
It's worth noting that the 5/1 and 6/1 engines are identical, just with a different RPM rating (600 for the former, 650 for the latter). The engine serial number plate should also specify the RPM (also the spec number).
Cheers!
Ade.