Boy, am I getting blind in my old age, or is it just my short term memory; it is a lever over guard, with third fastener in rear lump. No wonder I couldn't see a "Purdey" third fastener rib extension.
An exceptionally strong action, weight a bit high for .375. Just right for .450 nitro; would probably finish at 10 lbs. 8 oz.
A new hinge pin would be done with re-barrel. Hook and lumps of original barrels can be cleaned up and re-fit with micro-weld; I haven't seen too many that were beyond restoration. Still a very expensive project. I wouldn't want to pay much over 10 K for the gun "as is" if stocks etc. are ok.
What is the present gauge, and weight? It looks like a 28.