I think Uberti screws will work in the brass trigger guard.
These screws are the one that joins the backstrap to the trigger guard and the front of the butt, and the screw that holds the mainspring. I have a couple of Ubertis and will try them to see. Also thinking I may buy a brass backstrap and save this blued one for another gun I don't have yet.
My wife finds it amusing that parts appear in my parts box long before I have a gun to fit them to. She recently saw a hammer on my desk and asked, "Is that going to materialize into another gun?"
P.S. It did.