The “dovetail” is that triangle at the base of the sight where it goes into the barrel. The rear sight is the one you adjust for windage.Just use something like a brass drift & hammer to drift it right or left. The old timers would file the notch on the rear leaf or top of the front to fine tune the sights. As far as after market sights, I’ve got an XS ghost sight set on the Marlin 1894 and the Williams peep sets on the others. Some places sell the rear Williams peeps by themselves, but I found it’s better to get the set with the fiber optic front from someplace like Natchez.com

http://www.natchezss.com/product.cfm...Title=Williams Rifle Fire Sight Peep Set