Hey Doc

Post a picture or two if you can. It sounds like you have an older Porter or Mahan Class destroyer, or an early version of a Fletcher Class. I would kind of bet it is a Fletcher class. I would need to see the gun arrangement.
The Fletchers have three 5 inch singles on the stern, the older two stackers have only two mounts on the stern, and are some times unsheilded. Is there a step deck?

The Fletcher class in 1-48 scale should come out to 92.25 inches(369ft), and the older destroyers should measure around 83 inches(334ft)....

There is a "Benson"/Gleaves Class of US destroyer that measures out to 87 inches, and has the three stern 5 inch guns. However I am not sure they had rounded bridges and the Fletcher class were known to have that style of bridge. The difference here is that the Benson has a step deck, and the Fletcher were flush deck bow to stern.

I don't think the ship class matters, Actually, I just want to see pictures....