Recently put a skinner rear peep and front partridge sight on a 1978 Marlin 1894, 44 mag.
Service is first rate. Order was missing one item that was immediately sent, no hassle, and received in a couple days. http://www.skinnersights.com
Rear peep fit perfect. The .450 front needed some filing to fit and shaved down to .410 for me. Note my front ramp is aftermarket and may differ from stock height. Helpful instructions are included.
Have a Williams peep on another lever that has the advantage of being easier to adjust if changing loads but not near as sturdy as the Skinner. I set it for my full loads of 2400 with a 245 gr. Keith SWC. Trying my mild loads of the same bullet with unique I can hit a 10" steel plate at 100 yds. on the same setting.
There are previous threads on the sight that can be found with search.P1010728 1.jpg