Rimfire peep sight for 3b

Hey guys!
New guy here, been shooting since boy scouts, can't get enough.
Seventy now and still at it.
Just got a Mod. 3b from a fellow club member, it has the base of a
lyman 55S peep on the receiver.
There is no aperture or horizontally oriented part for it to attach to.
The receiver itself has three drilled and tapped holes in the left side, two are holding the sight now and one slightly larger appearing hole is next to them on a slightly different line than the others.
I like to restore older pieces like this and pass them on in better shape than I got them.
What can I do to replace this base, or find another period appropriate sight to make this a nice little target rifle for a kid
or such. It is in very good condition w/a good bore and xlnt stock. about 85-90% blue I'd say.
Any ideas?
Also have a very nice 722 in .300 Savage, all original except for sling swivel holes in the nearly perfect stock, blue 95%.
Any one interested in a swap perhaps?
Hope to have a lot of fun here, love vintage rifles, single shots, and nice shotguns.
Be seein' ya!
desertt dogg