Need advise on early Winchester resto

[painter777]

Find a local Body/Fab Shop that has a Pinch Type Electric Spot Welder.
Couldn't Imagine it would be very pricey for a couple of Spot Welds.
No after grinding needed.

Also,
Your front sight is like many that had the side ears bent off for better sighting in low light conditions. My Father said this was very common in the PTO during WWII.
Your replacement doesn't have to be 'L' marked, most in this serial range were unmarked but made by Lyman for WRA.

HTH,
Charlie-Painter777