It's the front sight change on those, that's the catch.
The square post on every one I've had (four) were solidly engaged to the barrel (I believed they were hard soldered or welded in) and needed to be either milled off, or have a fore/aft slot milled in the top of the sqare post (after cutting off the thin top) for a handmade blade of whatever height needed with whatever bead material (Ivory/gold/fiber optic).
As for peep sights, the m92 will accept any peep sight originally meant for a Winchester 94.
If the M94 peep is a side-mount peep, the side of the M92 needs two holes D/T'd for it on the left side near the locking lugs.
If the M94 peep is a top-mount (for a 94AE) then the top of the M92's receiver side walls/rails need one hole D/T'd in each side just ahead of the locking lugs for that sight.
If the M94 peep is a tang sight, the issue height front sight will zero OK, and the rear tang will need one hole D/T'd for the tang sight's forward base screw, with a longer screw replacing the original stock tang screw at the rear of the sight base.
If you're interested in thinking outside the box, the Williams WGRS peep for a Browning BAR has the same base contour as the top of the M92 bolt, and can be mounted on the top/rear of the bolt via D/T, but needs a much higher front sight.
A small XS peep may also work atop the bolt, but I haven't tried any for the proper base contour.
BTW - Any peep sight can be used as a ghost ring sight via the simple expedient of completely removing the sighting aperture and shooting through the resulting large ring, for speed.
Proper "ghost ring sights" are just peeps that haven't been threaded for apertures - which are more accurate when zeroing/etc.
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