What about one of the first, second, or third model dragoons, which are Colt's own improvement on the Walker.
The loading lever on a Walker is a built in defect, that you can't fix, for sure. I always thought that if I got one, I'd have a dragoon loading lever adapted to it. Now that would be a neat gun. I think that lever dropping about every other time you fire the gun will really kind of ruin it for you.
Whatever you decide, it sounds like you would be more happy spending a couple extra bucks, and getting a Uberti. They really are high quality guns, although I have heard of a few lemons getting through. I have a Uberti New Model Navy, and it is truly nice, I would not trade or sell it for anything. My hunting partner just picked up a Uberti Navy Colt, and it is the nicest I have seen, beyond a doubt, bar none.