I raised the block walls on my shop years ago (I didn't build the shop originally, just remodeled it and added onto it) from 9' tall to about 12'6" tall. The shop stood for 30+ years with not a single pilaster. Anchor bolts were merely cast into mortar on the top course. When I extended the walls up, I poured pilasters with #4 rebar on 56" centers and at corners and door jambs. The roof structure will blow off of my shop decades (maybe centuries?) before the walls fall over.
BTW, I'm a concrete and masonry contractor. I deal with stuff like this regularily. If there's one thing I can't make clear enough, DO NOT fill the entire block wall, only fill pilasters. And, pilaster grout is not the same as ready-mixed concrete. And, when it comes to grout, this is one area where stronger isn't better. People here tend to "over-kill" in their mind, but don't realize that they are actually causing more damage than good to the structure.......
