Does this VO headset look like this?
https://velo-orange.com/products/headset-parts
The "split race" is a split sleeve with shoulder that slides easily over the crown, then the race itself slides over that sleeve. I've never seen such a headset, but then, I haven't seen everything.
I know this sounds like a broken record, but I am a huge fan of Tange headsets. Very consistent, never issues. Go reliably (at least for me) 8k miles before too much indexing, than another 1k with the next ball size up. Readily available in well marked packages. You can mix and match parts from different models and diameters to fit virtually any 1" steerered bike and stack height. Full quality chrome that takes wrenches well, even on their (very low stack) $8 OEM replacement headsets. The Passage fits my custom ti the best with a locknut from the cheapie. $14.
Ben