The sidelever guns I've worked on have the lever mounted in the trigger plate, why a conversion like this would be attempted is beyond me. If done at Dicksons, one would think it would have been easier to just make another gun. I don't know what the side locking bolt is, you can see the underbolt in the first picture.
The junk in and around the knuckle is the biggest problem I see. I'm pretty sure that got done by someone else, when they stuck the barrels on. They were probably adapted from another gun, hence the dog which needed to be fitted to work the extractors, rather than the toggle that Dickson non-ejectors use. It may have been a non-ejector first, then converted to the early pattern ejectors, then those have been removed and plugged. It's a mess.
It's all really hard to tell from pictures - having it your hands (or better still, taking it to pieces) would tell the story.
