If you are looking for great sight products for Marlins look here: http://xssights.com/ http://www.skinnersights.com/ http://www.talleymanufacturing.com/ Talley makes a nice "extra low" lever mount thanks to the help of "Jake" and others on another forum. They also give a great Military discount!
I have Skinners on my 336 30-30, and on my 1895G 45-70. I am very pleased with them so far. I plan to add one to my 39a in the near future.