[Chriszuma]

what we do is drill a hole the diameter of the bolt through the piece, and find a piece of round aluminum tube that fits the bolt inside it. Then on the side that will have the part attached, drill the hole large enough to accomodate your tube. Cut a piece of the tube so it is flush with the outer edge when you sink it into the hole. Then sink your new spacer into the hole and bolt your stuff on, putting the bolt through the tube. It's definitely the most effective method, because you can put insane amount of torque on it and it won't deform the squareness at all.