MVA makes a quality sight. Their sights are competition quality. If he is into the "old style guns", and will eventually get a Rolling Block, a Sharps or some other old school rifle (even a musket) an MVA will never let you down and can be used in all those rifles.
This is the type of scope that will last decades if properly taken care of.
montanavintagearms.com
Another option is a soule sight. A good soule sight is faster than regular irons and a scope, the only downside is that a Smith will need to drill the butt.
MVA Soule sights are excellent, so are Kelley (I use Kelley). Kelley are old school looking. Will also fit any antique style of weapon and they are not out of place, they were used in the late 1800's.
All the products that Kelley Sights make
kelleysights.com
I am stupid fast and accurate with a soule.