Body Mods
There really wasn't much to do to the body itself, fortunately. We had decided to upgrade the controls to CTS pots, and to add a small toggle switch for the coil tapping. CTS doesn't seem to make pots with push-pull switches, or at least we couldn't find any. StewMac sells CTS pots without switches, and Alpha pots with and without switches, but we wanted to stick with CTS. This required two mods.
First, the CTS pots require 3/8" holes, but the original pots that came with the guitar were in 5/16" holes (probably actually metric). Drilling a new hole in a guitar is scary enough, but trying to enlarge an existing hole with a drill is another story. We drilled a 3/8" hole in a piece of scrap wood, put some masking tape on the back side to prevent any scratching, and clamped it with the hole centered over one of the control holes in the guitar. The F hole made clamping the scrap wood fairly easy. We used the hole in the scrap wood as a guide for the 3/8" Forister drill to keep it from wandering, which worked like a charm.
Second, we needed a new hole for the mini toggle switch that would be used for the coil tap switch. We marked up a spot on the body with masking tape, and again used a Forister bit. The Forister bits work well when drilling through something that already has some sort of finish on it. The spurs on the bit cut a clean hole through the finish before biting into the wood.
Drilling the control holes to the proper size for CTS pots
Once the holes were drilled, we replaced the factory pickups with some nice Seymour Duncan humbuckers and some pickup rings (all of which I had found on eBay), which were drop in replacements and fit nicely without any further modifications.
The most complicated part of this upgrade was wiring up the harness and getting it all back into the guitar...