Unfortunately the original THR and Remington 1858 Forum threads only mention that the Wolff 32280 spring worked in the Pietta and Uberti 1858's. --->>>
https://www.thehighroad.org/index.p...emington-trigger-spring.870616/#post-11547859
That doesn't mean that it won't work in your FIE - PR made reproduction.
But best to be careful before shortening it because it is a weaker spring.
It's easier to take metal off than it is to put it back on.
And we don't know which major manufacturer provided the frame and grip frame for your gun.
Most other makes accept Uberti parts, but unlike with the 2012 Uberti 1958 mentioned below, the springs are not the same size.
While the new spring may be longer, if you unnecessarily shorten it to fit then it may not function as intended.
Perhaps simply bending it into place to install will be good enough, or perhaps not.
Good luck with however you decide to get it to fit.
According to the original thread. that 32280 spring worked:
" In addition to fitting in my Pietta 1858s, it also fits in my Pietta 1860 Army. However, in the 1860 Army, there isn't enough force to reliably fire the cap........
.......The 1858 Pietta works the first time, every time, zero fail to fires with the 32280 spring."
And:
"My 2012 Uberti Rem took the 32280 Colt SAA spring, by Wolff. It dropped in and, after tightening the tension screw, functioned perfectly........
.......Yeah, I like the spring a lot. I compared the 32280 to the stock Uberti Rem spring - they were the same length." --->>>
https://1858remington.com/index.php?topic=5248.0