Hey WOT,
I kinda have had the same question with my 20 stoker with 200 merc. I have what I think is a bronson Hill Chopper 25" and I pull down about 80 by myself turning about 6300 rpm. I am seriously about to buy a couple Mercury Lightning ET props one with 28" pitch and one with 30" pitch. I have read so many amazing things about this prop for about a year now that I am convinced that it is right for me. One draw back though, it can be prohibitively expensive at nearly $1000. I have also considered buying a Ron Hill propellers Lightning ET knock-off but have heard some negative things about his props construction so I am not sure who to believe.