60# is enough for any North American game so I'd choose a 50-60 to begin with. If you are just looking for now you might even look at bows in the Martin line as they have a 15# range. ie.-45-60 or 55-70.

Take into consideration that bows today are much more efficient than those of just a few years ago. What you might have thought you needed 70# for can be had with 60# today. A lot less wear and tear on the shoulders as well. This will become more evident as you age so no need to help the aging process.