I'm not a big fan of Uberti repros, however, the mainspring and trigger spring may be very different as most originals(early ones) used leaf springs, the leaf type lever spring is attached to the barrel, on originals. My 1901 original 1885 "low wall" has all leaf springs, my C. Sharps "Highwall" has newer coil springs, I don't know whats on Ubertis. I would think you would be better off to source parts from Uberti, as they would be easier to get, cheaper, made for the rifle and shouldn't need altering. There are many places to get parts for original 1885s in the USA.