RHB,
That shiny area where the ribbed part is, is the wedge shape you speak of. The ribbed area is what they either (earlier) ran a set screw into to secure the sight, or (later), just peened the sight in that area. I have several 1903A3 sporters with no rear sight, tapped however for scope bases. The one in the photo is intact and undisturbed. I'm assuming from the OP's description that it has barrel mounted sights.
Yes, one could find the appropriate barrel and stock plus hardware and restore it but it would be restored and the cost would still be iffy. If you had parts sitting around, well, I suppose what the heck. Any good shooter that's pretty much correct is worth $400-$600 give or take.
I know it's getting harder and harder to find sporter for decent prices anymore. I think I paid $340 for the last Smith Corona I picked up for the receiver which was drilled and tapped. Sold the scope and barrel and recouped some of it.
This is what I did with the receiver;

IMG_1433.jpg