I used a Wiegand base on my 44's and 500's, and a Burris Fastfire 3 on both guns without issue. One of my 500's came to me with a stainless steel mount, but I have since sold that gun and don't remember who made the mount.
I custom machined the top strap on my 44 RM from a 2 screw to a 3 screw and mounted an EGW zero cant picatinny base, I shortened for the occasion. I mounted a gloss black Leupold LER 2-6 scope in Talley gloss rings. Holds up quite well. tits for deer hunting. Have the same scope on My Henry Big Boy 44rm lever gun as well. Not a cheap date but good, recoil proof scopes usually aren't.