i have a 6.5" 629 .44 mag that i shoot 1400fps 240 grainers with that i want to put a rear sight on. (it has a scope base now) i'm looking at millet rear sights and the choices are .312, .360, or .410 height. which one would be best for a 50 yd zero, possibly 25 yd. or if anyone has a factory or aftermarket rear for sale.