Or rather, I hadn't gone back to see whether they needed more work.
I started with a coat of Tamiya X-19 Smoke, which settled down into the grooves after I wiped it off the high spots with my finger. Think dark wash effect.
BTW, it's great for grilles too.
Then a coat of semi-gloss black very carefully brushed into the 'slots'.
When I've built '66s previously I've toned down the spokes with a light metallic grey. Maybe it's time I looked up a real '66 to check!