I would definitely be talking to Galazan at some point prior to going off on your own with barrel bending or stock alterations. If your patterns are acceptable with the open chokes and shooting low with your tight choke tubes there is an outside chance that you have some bad choke tubes.
Try patterning both to see if you have the same problem so you will have a pretty good idea of what is going on when you talk to Galazan.
Before you do that I would also recommend that you pattern like you shoot. That is raise the gun acquire the center of the pattern board and fire. See if that affects your patterns placement. Looking down the rib as in sighting a rifle will often give you an incorrect pattern placement because you are, for lack of better words, squeezing your cheek into the butt stock and lowering your eye position.
May not work for you but it is worth a try.
