Mark 9 was early, heavy version of 8in/55 gun.
Externaly versions 10, 11, 13 and 14 were very similar.
See also MASTER set with late "lightened" version of those guns:
SM-350-025 - USN 8"/55 (20.3 cm) Mark 12 barrels (9pcs)
Used on following USN warships: Lexington (CV-2), Saratoga (CV-3), Pensacola (CA-24), Salt Lake City (CA-25), Northampton (CA-26),Chester (CA-27), Louisville (CA-28), Chicago (CA-29), Houston (CA-30), Augusta (CA-31), New Orleans (CA-32), Portland (CA-33), Astoria (CA-34), Indianapolis (CA-35), Minneapolis (CA-36).
The set includes turned aluminum barrels. It is very simple to use in Your model, and makes it extremely realistic. Simply cut off the original plastic barrel and drill a hole in the remaining part and insert the metal barrel using Cyanoacrylate adhesives.