I've started on the rear wheel for no particular reason other than I expect it to be more work and secondly it's easier to get out than the front one for which I need to remove the wheel stop on the bike lift.
The first step is to take a wire brush to the sand cast aluminium surfaces on the inside of the spoke flanges. You don't want to scratch the outer polished faces because it will be the devil of a job to remove the scratches made by a steel wire brush.
For the outside I have used a combination of 180 grit Scotch-Brite pad and a degreaser. This reveals a nice groove which whilst it looks quite uniform has actually been worn in place by the sharp edges of the chain case. When it's clean you can see that the bottom of the groove is quite rough:
This progresses through the 150 and 300 grit wheels to the polishing mops:
It doesn't take long before it's ready for lacing on the rim.
Shame I have ordered the wrong spokes. It's shown here sitting on a 1 1/8" post, clamped in the Workmate, turned to just under 1" to allow the hub to slip over it. We'll lace the wheel in that.