Do any of the current receiver mounted peeps on the market fit the factory drill & tap'd holes on the upper rear left side of the receiver? If so, which ones. I'd rather not have to drill and tap my late 50's vintage model 94 if I don't have to. Thanks.
Let me say this, I wouldn't have one of those cheap looking Williams receiver sights on any rifle of mine. They wouldn't fit your pre-64 rifle, for the same reason the Lyman 66 series won't work on your pre-64 Winchester 94.
The Lyman 66 series of receiver sights won't fit your pre-64 Winchester, because your rifle is utilizes top ejection, of the spent cartridge case.
Lyman did make a receiver sight for your rifle, a long time ago. However, you needed to drill and tap the left side of the receiver to install it.
If you want a sight for your rifle, without drilling and tapping, your only recourse is to install either a Lyman or a Marbles TANG sight.
If you install a Lyman tang sight, you will have to drift your front sight from side-to-side to adjust the windage. Not a good thing to do, if it were my rifle.
Marbles has a Tang sight with the windage feature built into the base of the tang sight. I have installed Marbles tang sights, with the windage adjustment feature, on several of my lever guns.
Bill