If you ream the hole out bigger and don't do anything else to hold the bolt, it will slide out of adjustment not matter how tight you tighten it. If you want to try the reaming idea, ream out the upper hole in the strut, not the spindle, then use two big thick washers, one on each side. Once you have the camber set right, weld the washers to the strut bracket so they can't move.