Welcome to the site.

Can we see some more pics, maybe side views of the action and stock, the whole gun, etc.?

Assuming the gun is operable and tight, it should be no problem for pheasants - just another 16 ga that way. Try some 2 1/2 inch RSTs - it will almost certainly have been made with 65mm chambers and the wood is a century old (if it hasn't been restocked).

fiery, dependable, occasionally transcendent