Nice find. I note the round cylinder lock notches, whereas the current Uberti Walker has oval notches.
I'm convinced that the stories about Walkers loosening up under full house loads come from guns with short arbors, which can batter themselves due to the loose fit between barrel and frame. There's pretty scant contact surface area between the wedge and barrel, and the wedge steel isn't very hard, and so a little "jangling" between the parts could easily result in peening.
Before I ever fired the gun, I shimmed my Uberti Walker arbor so the wedge can be tapped in tight and not jam the barrel against the cylinder. That provides a consistent and repeatable cylinder gap and barrel-to-frame angle, with no (or greatly reduced) movement during the violence of firing. I've fired a couple hundred rounds with 45 and 50 grain charges of Olde Eynsford 3F powder (more energetic than regular Goex, and close to Swiss) with 200, 225 and 240 grain bullets and no sign of loosening has yet become observable. I'm confident I could shoot those loads, or a sixty grain 3F charge with a round ball, for years and years and not have a problem. I don't know about an ASM, but the Uberti can handle it once it's been fit proper.
Anyway; that's my observation so far, and others have tried this and concur. It may change over time, maybe.
It just depends on what you want to do with it. The Uberti is readily replaced, and so I didn't feel there was a lot to lose by experimenting with it, plus I wanted to see what a chamber that size could do with the 9" barrel.