Shimano 105 calipers are short reach road calipers; they're designed for a max reach (distance from center of mounting bolt to center of brake track) of ~49mm. The longest reach road calipers to my knowledge are Tektro R556 with a max reach of ~73mm. I suspect the distance on your fork is beyond that. The drilling in the fork is commonly used for attaching fenders.

You can use your choice of v-brakes or centerpull cantilever brakes. Incidentally, I can't see what is bent on that brake.