well your pretty heavy for the 151 but your height should be correct. You should be okay with the 151 though, I think the 156 might be too big for you. Im 6-5 and I ride a 158.

 

Jeremy Jones is a big guy. that being said, he typically uses the 51 for rails and 56 for jumps, when you're a pro, you can have two sizes of a board with you. especially when its your pro board.

at 180 though, I'd say the 156.

Good choice on the board, its the only burton I've ridden that I liked.

and get some EST bindings for it. It rides soo much better with EST's then retro fitted others.

 

at 180 though, I'd say the 156.

I'm going to have agree on this. I'm 6', 170lbs. I rode a Twin '54 last year for Park, and it could get pretty slow at times. For your weight, I'd go with the '56.