Yes it seems that most cantilevers had the post mounted "outboard" of the arm. However, you really need to compare whether the brake pad post is really any further away from the fork or seat stay. It may be that the brake arms are just manufactured differently (I suspect this was for ease of setup, maybe), but the brake pad posts are almost all the same distance from the fork or seat stay. But you are correct, the further out the brake pad post is, the more torque you will get on the brake boss, and the fork or seat stay. The more torque, the more twisting you can get. This is one reason that cantilever brakes are commonly toed in; as the fork/stays twist, the brake pad becomes flatter on the rim. By the way, I use cartridge pad holders so that I don't have to reset everything when installing new pads. Oh, and nice polishing job.