My dad and I did a budget build on a Mosin, we drilled and tapped the receiver ring for a Williams receiver sight. (And other mods/upgrades to make it more civilian)
All in all, it was a very good conversion, and the peeps worked nicely, with the shortened barrel. My tickle trunk had the sight, the only expense was for 2 taps, one broke, as the metal is not soft or easy to work with. We did the work with basic hand tools and a hobby drill press. We soldered the front sight on, a Rem 788 sight cut down to match the rear.
One point, if you add a peep to a Mosin (non sporterized) beware that the hooded front sight will mess with your mind. The post is not in the center of the hood, and your mind will want to do 1 of 2 things, center the 2 circles or center the post in the peep, or both. It really messes with anyone that borrows your rifle and shoots a good group, a foot to the left and 18 inches higher than you just did.
Looking through an aperture will correct for myopia (near nearsightedness), but if you are far sighted, perhaps not so much. As stated already, peeps extend the range of focus, and I think that is true for normal as well as for myopia, I don't know what it would do for hyperopia (farsightedness).
The military conscripted young people, and if you look at old WWI footage of the trenches, not too many wore glasses.
TTFN