A few interesting thoughts. First, the wedge and loading lever screws are correct; the Walker is the reverse of later guns, and the wedge and screws go in from the right side.
The serial numbers are in the right place and seem to be in the right font. More interesting is the dovetail cut in the barrel where the original lever spring has been removed and replaced by the much later style lever latch. That was a common gunsmith/armorer fix with those guns as the original type spring very frequently broke, but there is no reason a faker should make that cut when he was not going to use it.
It could be a worked over repro, but why alter it in just the way those guns were altered back then? If the lever spring broke, why not just order one from Uberti or whoever?
If that gun were for sale at what some of the folks say it is worth, I just might be interested, but not at $4500. And I would sure like to get a good look at it.
Jim