Welcome to the CSP forum loco_engr. I'm always fascinated by the ways in which those who came before us chose to modify, and personalize, what were at the time inexpensive surplus guns. Possibly one of our more knowledgeable members will be able to tell us whether your receiver and barrel began life as a rifle or carbine. The workman clearly wanted better sights. Whether this was for hunting or target shooting we may never know, but if this was originally a full length rifle it wouldn't seem to make much sense to cut it down to carbine length for target shooting. I'm curious to know how the bore is and, most importantly, how it shoots.
All in all, it's a neat looking little gun. A skilled smith could redo the filling of the rear sight holes so as to be virtually unnoticeable. When you say the forearm doesn't appear to be original, are you referring only to the checkering or does the wood appear to be spliced? The fact that the prior owner scratched his social security number into the butt plate adds some interest. I for one would enjoy seeing more pictures, just to admire the piece for what it is. Thanks for posting.
"They've took the fun out of running the race. You never see a campfire anywhere. There's never any time for visiting." - Joe Redington Sr., 1997