That's a bit of a rare hub there Ted, the slots are very useful for those doing the twin front disc setup as the slots are the locating lugs for the speedo drive.
You could try chrome ceramic coating, like the carb plate I sold you. It's called Cermakrome. Camcoat do it in Warrington if your stuck finding somewhere. It's a lot thinner than powder coating and I'd refrain from powder coating the flanges where the disc fits TBH in powder but ok in ceramic.