According to Parts Catalog PC158, the 347 share is a 14 inch.
The EP314 JD on your moldboard is a bit confusing to figure out from the Parts Catalog. It lists it as 10, 12, or 14 inch. Maybe you had to specify which size you wanted when you bought the plow. The catalog also lists the moldboards as Sod Bottoms and the shares as Breaker shares for use with Breaker Bottoms. But the drawings for Sod and Breaker bottoms shows them to very different in shape.