Don't even think about putting glass on a fine lever action (Blasphemy!!!) A ghost ring sight is the only way to go. The best made are from a company called "XS Sight Systems" (formerly AO- Ashley Outdoors). It is called an express sight. Fast, accurate, light weight and rugged. Unfortunately when I pull up their web site is a dead link. I hope it is only off line and not out of business. The only working link I found is:

http://www.xssights.com/

If XS Sights has gone "teats up" there is a decent lever action gunsmith in Montana that has some really nice peep sights as well.

http://www.brockmansrifles.com/

If you insist on glass, Brockman will customize your lever action with a forward mounted LER scope, ala "Scout Rifle" concept.

I just did a bit more surfing and it looks like XS Sight Systems (aka AO- Ashley Outdoors) also makes a do-it-yourself scout scope mount for the Marlins. The Outdoor Super Store, http://www.outdoorsuperstore.com, sells the AO scout scope mounts and the express sights.

I think a properly set up Marlin Lever is one of the finest survival rifles around.

Good luck,

TR (Lever Lover)