The barrel is not a difficult change but it is threaded.
And you'd need a Mushroom ejector rod to look right.

Neither are simple to find but they are around. The barrel still wouldn't have a matching serial # however. And wouldn't add as much value as it would cost you because of the pitting on the gun.

I would just add the mushroom knob because it would make it look right. The barrel on it is better than any replacement barrel you are likely to find. Although it would have the proper "PROPERTY OF US ARMY" roll marl underneath.

__________________
Jim
S&WCA #819