Well, I ended up installing Active "Reflex" pickups (blue dot) on this guitar, and it sounds fantastic! I sanded the bottoms of the rings flat. I had to re-replace pots (fewer ohms) and then yank out the shielding (after all that work) to make the Reflex pickups fit. The battery is just squeezed into the control cavity. Later I would like to route a special battery cavity to make it easier to check the battery power and replace the battery.