Yup that's Elliason rear sight, the old GC standard.This is what the gun looked like NIB. My my eyes the sights, trigger and grips have been changed. Sorry for your loss. I would keep it just as your father set it up.
Actually just found one in an envelope w some Wolff Commander recoil springs.
Pops had several GC's over the years, and the last one was stainless.
I dunno if this sight came from it or was a spare.
My preference is for the Bomar, of which the OP's Wichita is very close (close enough).
I even changed out the Elliason and ramp front on my Python to Kensight.