That is a 1911 "undercut" slide stop which is as it should be (blued). In good condition that slide stop alone is worth $75-$150 if it's a COLT and could be worth alot more if it's a USGI Springfield Armory or Remington UMC mfgr.
As for the rest of it.
Looks like a correct (for 1944) Type 3 slide.
The feed ramp on the frame should be "in the white". Should have an 8 rib mainspring housing, serrated slide stop, checkered stubby hammer, and stamped trigger. It could have either a High Standard (HS) or Flannery Bolt (F) barrel depending on where the SN put's it being mfgr'd in 1944. Any USGI magazine is technically correct but as a Remington Rand it should have a "G" marked, welded back General Shaver magazine....
Your pics are horrible as far as evaluating the condition but I can still see wear on the sharp edges and a lot flattening of the checkering on the right grip....
A CORRECT Type 3 Remington Rand in the shown condition is about an $700-$850 gun IMO....
A correct slide stop is gonna cost about $50-$100 and it's gonna take a while to find one that matches up decent with the wear on the gun.
No serious or advanced 1911 collector is going to be interested in it because of the wear and wrong slide stop. However there is a buyer for everything and nostalgia running as high as it is right now it could fetch more than that from a less educated buyer.
Will