New Humbucking Flat Pickup Ring Set Flat Bottom Chrome | eBay
They were just these generic flat metal ones.
Note that the guitar's pickup cavity did have to be routed slightly larger and the screw holes for the humbucker ring did not line up either. I had a tech do the mod for me since it was out of my own personal comfort zone.
Crazy that you found the Lollar to be darker than the stock ceramic. I found the opposite. Yes I agree that the bridge FB pickups are too Tele-like for my tastes as well. I wanted more of a normal "rock" sound for the bridge, but like the snappiness of the FB neck.
Peace
Dave