Keep in mind the wheel axle castings are the same on both sides of the B. So the holes for the mounting of the plow on the front of of the castings are the same layout for the holes that mount the regular drawbar on the rear of the casting. The three holes (at least on my B) are to adjust the height of the regular drawbar. Since the plow drawbar pivots very closely to these holes, I don't see these holes affecting the adjustments as much as the plow drawbar lever.
Are your plow wear parts in good working order? If they are worn, the plow may not do a good job no matter how well it is adjusted. My two way plow has only been used a few hundred feet while I play, and are mostly for show, so I have not had the chance to play with the adjustments on a large stretch of land. Detailed Pictures of my plows mounted should be in the archives somewhere if you search for my "handle".