The gun was re-proofed in 1986 in London.
State of prood in the USA is a bit of a red-herring unless you are looking to sell as it can effect value but has little to do with safety.
Wall thickness, barrel condition, changes is chamber length, lump integrity and jointing are the important safety issues.
Chokes can be 'adjusted' by use of appropriate ammunition.
The fact that it is marked 2 1/2" does not mean it is still so chambered. Many guns in the USA have had their chambers 'dropped' but never re-proofed. Best to get them measured.
Enjoy!
