As an afterthought, You can do this two ways, drill completely by hand with the shims in place or make a starter hole with the shims in then remove the neck and do it in a drill press, which is how I would do it, but I have a machine shop to work in, depends on what equipment you have available.
You can also put a very small dab of silicone sealer on the shims to keep them together and in place in the heel pocket when you are lining up. It will peel off later or you can leave it if you are going to drill and screw without cleaning out the dust.