Brian ... yes you can adjust it in almost any direction, uppy, downy, lefty, righty, cantedly forwardy or backwardy ... it is up to you as to which way you adjust it to fit you as long as its within the total allowed adjustability factors of the comb.
I never thought of canting comb to get it level. I just "assumed" there would not be enough play in the posts to do that. I checked mine and with 3 spacers in the front and 5 in the rear, the front of the comb is even with the top of stock. The rear of the comb is still about 1/16" low (from being parallel)but it's not that noticable. My post is not high enough to get a 6th washer on it. Hippo may be using different washers. I used the ones that came with the gun.