UPDATE
Well, I have both of them and it turns out the 783 Marlin .22WMR was made in the first year of production (1971) and the Glenfield 25 was made in 1974. These both exhibit early type front sights, no warnings engraved in the barrel, bolt and stock variations consistent with the earliest versions of both rifles, etc.
The 783 has a 4x JC Higgins scope mounted which probably came from an older rifle as the J.C. Higgins line was discontinued by Sears about mid 60's and replaced with the Ted Williams store brand. The scope is a bit dim as typical from the era but turrets work and the sight seems well mounted and not loose. Both have mirror bores and are mechanically in excellent condition. The Glenfield was missing its magazine so I bought a new old factory stock replacement for it.
There are some minor dings on the stocks with the 783 has a nice walnut stock with a pressed inlay design like Gunnie's rifle above but with a poly finish that is a bit skinned up in a few places, the Glenfield is birch with a dark stain but a few less dings than its sister. Both are missing stock sling mounts leaving holes in the stocks where these were. Some rust on the buttplate screws but both are not cracked, the Glenfield is blank as usual and the 783 has the Marlin markings on the buttplate. Minor damage to takedown screws where the wrong sized screwdriver has been used. Probably just swage the screw head material back in place.
Pictures and range report to follow.
In sum, I might spend $20-30 bucks to refurb both (replace buttplate screws with brass, replace the missing sling mounts, replace the plastic Glenfield trigger guard with metal, and may refinish stocks as I prefer oiled stocks rather than poly.
Now, the $64 dollar question, sights?
Did anyone make aperture sights for this series of rifles? Are the two holes in the sidewall of the Glenfield 25 and Marlin 783 for gas venting or for some sort of sight mounts either scope or aperture sights as these are tapped?
Pardon me but this butchered example from everygunpart.com (not the one that I bought btw) shows the location of the tapped holes in the receiver sidewall at the rear (the part with the trigger mounted) that I am talking about. They are 3/8 inch apart o/c or so (.375) in.