If you can get use of a vise and floor drill press, you can do this accurately. First lock the drill chuck in the down position, find a piece of blank shaft which fits snug in the hole, chuck in the protruding part of the shaft with the bridge sticking down off of it, then carefully position the bridge and lock it into the vise using shims so that the shaft can move smoothly in and out of the bridge leg. Remove the shaft and replace it with the proper size drill bit (1/4"?), and drill out the hole. Otherwise, this would be quick work for a machinist with a horizontal mill.
Edit. If you have a machinist buddy, he could quickly turn down the diameter of the non-threaded side of the pickup, but this might be a bit risky.
Last edited by robobass : 01-15-2013 at 02:13 AM.