Well, 2 months after buying the bike, I've got the final bit of re-registration done. The bike had to go through an inspection (its one and only MOT, ever ) on 23rd February, then chose the new index mark (£9 for next in the list, £67 for chose-your-own, if available) and got the bike registered on 8th March. The new insurance certificate arrived yesterday, and got the new tax disc this morning.
Enter the new Manx African
An apt registration, I thought
Found a reasonable place for the tax disc too, up on the engine