I'd only use what Roval designed for those hubs and nothing else as it pretty much a proprietary design. "Forcing" something to fit/work on a critical item like a wheel is just taking to much of a chance IMO.
I've been also eying Roval wheels for my French 80's bikes in the last couple of years, but I never could pull the trigger to buy them when I find them as I am nervous about the availability of replacement spokes......but I suspect you can eventually find them if you try hard enough as we always find out that C&V bike parts and components that we think are extinct, seem to eventually come out of the woodwork and end up for sale at eBay from time to time..... I think C&V Roval wheels are in my future,...... just need to find spare spokes to go with them when I do decide to buy a set.