Steve,
I am sorry to learn about your situation. Life can be tough on gun collections.
The 20 gauge is a good choice for a whole number of reasons. The gun should be fine in the uplands and its Cylinder barrel should be able to throw .610" round balls at least as well as any Northwest gun.
You make a good point about wads. FWIW the lubed wads that I was thinking about earlier were T/Cs. I understand that Circle Fly's lubed filler wads work well, too, but not for all of the same applications as the T/C wads.
One thing that I forgot to mention was nipples. By and large, "stock nipples" on Italian shotguns are junk. Install "quality" nipples like "Hot Shots" and it will be hard to go wrong.
