We also started in our early 50's, and the limits that we put on our SLS profile was 40-60. But we didn't really pay much attention to that, if the couple that attracted us was outside those limits but otherwise attractive, we'd meet with them and see. At the club when we were looking for hookups, we didn't even bother asking about age.
My advice to you, MT, would not be to worry too much about age. You'll find attractive people of all ages in the LifeStyle. Just beware of immaturity and craziness, those types tend not to make good bed partners.