In that case I'd look at the 155 OG Flat. That's actually what I rode as my park stick most of last year.
For me at 155lbs the 151 made a killer park board that I could jib and jump, and the 153 made a good jump and all mountain board. So figure the 155 would fit like inbetween the two, but for you. So a little less jibbable and a little less mountain oriented.
Or do the 156 Omni and be totally set for park and all mountain.
OG Flat, huh? I'll check it out. Thanks!