I think the holes in front of the dovetail were part of a Malcomb scope system, since it’s d/t on the side of the receiver. I was considering putting the rear sight back on in case I don’t like using the tang sight. Can’t hurt I guess unless someday I put a Malcomb back on it. I’ll refer back to some previously posted pictures to see if they had rear sights. What do you guys seem to prefer rear sight or tang?
A point made in the Malcolm catalogs was that a side mount scope did not interfere with the original barrel sights leaving them for backup or low light. You can see in Joe's photo the Malcolm front mount is dished down so it does not interfere with the barrel sights.
The side mounts I have seen still have the barrel sights, however, it appears your gun has the holes almost to close to retain the barrel sight unless the front of the sight were shortened. From the protected blue & wear pattern it looks like your gun had a long rear sight on it for a long time.