Heck of a deal!
I'm not a fan of brass framed guns, but in the little Remington .31 I doubt it makes much difference. You can't get enough powder in that small chamber to cause much pressure or damage to the recoil shield, I suspect.
I'd jump on that deal myself. I have a fondness for single-shot .410s. I gave my brother the only one I had, an old Stevens.
Later, a kindly old gent gave me a lever-action Marlin Model 410 built someone between 1929 and 1932. It's not a common gun, and I appreciate his magnamity. Based on the Marlin Model 93 rifle action, it will only take 2-1/2 inch shells, but for close range hunting of grouse or rabbits it's great!
Between that little .31 and the .410, I'd be hard-pressed to decide which to shoot first.