Depends on many factors (type of dish, exposure to wind, the construction of the wall...) I have a single-brick construction on my shed wall, and a 1.2m x 1.35m steerable Gregorian mounted on a pole boldeted to (actually THROUGH) the wall. I have strengthened the mount by fixing plates to the inside of the wall at the position the bolts come through. Any bigger and I would have been risking a damaged wall in high winds...
Your location limits even more the maximum size of dish recommended, windage is a major factor when looking at installations at that sort of height, is there any way that the dish can be mounted on the roof? There are very good non-Penetrating patio mounts that can be used in flat roof situations.
Depending on the type of antenna you eventually go for, you will need the mount with the right post diameter
Channel Master dont make anything larger than the 1.2m with a polarmount and the next size up would be the 1.8m. You would have to make some bracketry to fit an aftermarket horizon to horizon mount (possibly Jaeger) to the CM dish
Assuming you are given permission to stick it on the roof, you could always try the Prodelin 1.8m with integral polarmount (they also make a 2.4m prime focus unit ) but I would agree with Rolf in that you have to be VERY careful that the right amount of concrete is put under the mount otherwise it will do some serious damage to the ground
I know that there have been problems on other forums regarding advertising of services. Certainly I don't have a problem with it but could see how others might. Perhaps any people who are happy to receive PMs regarding offers of equipment could state this in their profile or on their post.