I don't know anything about that board or what type or riding you intend to use it for but as a *very* broad generalization, someone who is 6'1" and 195lbs should be OK on a 164 for mostly all-mountain/cruising/groomers/etc.. But you would also be fine on a 160-161. Or a 156 if you're riding predominately in the park (where a 164 will be a noticeable hindrance).
where do you live/ride? do you want to jib rails/boxes?