Could be a newer head on the engine you found or even a newer replacement engine. If newer it could easily be a number eight looking like a zero. Some odd head numbers have surfaced over the years but nothing below a number fourteen I really believe. Minor casting defect is also possible I suppose where the sand or whatever fell away for the crossbar of the number eight before casting. The world is full of suprises.

It is not a number fourteen though in my opinion as there is no way misinterpretation of a number 4 and a 0 is likely. Of course it might be the first number ten head ever discovered for those engines but I do not think so.

Logically if the number 14 head was a further refinement of the number 10. God help people that may have had the number 10 ones..