RE: Made the switch tonight finally...
I am NO expert on what your setup needs to be to shoot mechanicals. I shoot an '07 Bowtech Allegiance on 66#'s. I KNOW my setup is sufficient. I can't speak as to what a minimium should be. I'll leave that to those who know, better.
I can tell you I would NOT be shooting any kind of mechanical head with a DW of anywhere near 50#'s.....ESPECIALLY out of an older model bow. I'd be shooting a COC, fixed-blade BH of some sort.