Height of open sights
 

Do open sights have to be identical in terms of height to function properly or can sights of differing heights be adjusted for compensation?

The rear sight is adjusted, pushed forward or slid back, for elevation.

Well, the rear sight goes up or down for elevation and side to side for windage. All else being equal, moving it forward or back won't affecr anything.

You sights will go further out of alignment as you adjust for range, bring the muzzle up to compensate for drop. In their base position they should be level.

If I was back in Canada, I'd take a picture of my Mk.I Lee-Enfield with the volley sights set for 3500 yards. At that point the muzzle is probably 25 degrees above level.