You have one rare rifle, I have never actually handled one.
I am looking at my 1960 Stoeger Catalog. This is what is in the Weaver Detachable and "N" mounts for a Stevens 417
Detachable top mount front: 15
Detachable top mount rear: 15
Detachable side mount; 2
type N mounts,
Scope Position Low: N2
Scope Position high: N3
From the pictures, a detachable top mount is the standard weaver base. The side mount was a plate, and there was a detachable split ring mount that screwed on to that. N mounts are for 3/4" scope, looks like something used for air rifles. It is a side bracket, two rings. Cannot remember seeing one.
I am surprised that there are scope mounts for this rifle. This rifle was built when scopes were just awful. The lenses were not coated, I have looked through very old scopes and the effect is having vasoline in the eye ball. And, they were long. This is a much later scope, but it would been similiar to what was available pre WW2. Long tube, external elevation and windage adjustments.
this is a pre WW2 rifle, and that is a Lyman Super Scope on top. And that was how the rifle was set up, though, probably a different scope.
I wish you luck finding rear sights. No Lyman, no Redfield hunting sights in my Stoeger. However, under target sights, a Redfield No 75. Part number 75HY.
Take a look at the 1944 ad before it disappears. I have no idea where to find a Lyman 52L, or Lyman 48L, or a Lyman 144.
https://www.ebay.com/itm/402617368274
It looks as though the Stevens could be fitted with a tang sight. I think tang sights are horrible. Slow to adjust up, down, and sideways. Would not be what I would use in a smallbore prone match. By the time you got the sight adjusted, the wind would change.
The front sight was a Number 63 with a 0.175 dovetail on barrel. Per description,
Globe Target Front Sight, 1" long, 5/8 diameter. No 63 quick detachable from separate dovetail or screw attached bases.
I think the front sight will be a standard globe front sight, no need to find a vintage. Lyman makes old globe front sights. Front and rear sight heights can be very time consuming to get right. I have several baggies of sight bases, especially as modern target iron front sights are much larger in diameter than the vintage ones. And going from a vintage rear sight like this
to a more modern one like this
took different rear bases, and different heights of front bases to get the rifle to zero. Or zero leaving enough Elevation to get to 100 yards. Steve Earle is the source for dovetails.
https://steveearleproducts.com/scopeblocks.html
He might have suggestions for what to use on a Stevens M417
