Neither the loading lever latch not the front sight on Pietta Remingtons are mechanically attached to the barrel. The latch and sight both have flat bottoms that fit into a flat bottomed slight recess in the barrel. I honestly have no idea how they are attached at the factory but I suspect they may be soldered in place. My only experience with one was on a Pietta I had bought my wife. The latch popped off and the recess in the barrel showed the same blue as the barrel which made me think it had never been properly attached, possibly only pressed into the recess. By the time this happened the revolver had been completely reworked and would be out of warranty not that that was a consideration given the rework. The nationals were only a few days off and my wife couldn't shoot the team and individual matches with the gun in that condition. I called Taylors and neither of us could make it there when they were open but Sue said she would be there at 6:00 AM loading guns and parts to take to the suttlers and I could come by. She didn't have a Uberti Remington latch but did have one for a 60 Army so I got that and a friend installed it. It really didn't look out of place and worked fine.
Epoxy may work for the sight but it won't last for the latch, too much pressure on it. I would suggest buying the latch, as well as the front sight, for a Uberti and dovetailing them in place. That's a permanent repair and you'll also have a windage adjustable front sight. Attempting to silver solder or braze it in place will ruin the barrel. Soft solder might work but I wouldn't depend on it long term myself.