The Jaguar D-Type wheels by Dunlop featured a spun aluminum center mated to a steel rim (or was it the other way round?). They are still being manufactured, since you see them on the better D-type replicas. These are peg-drive wheels, meaning they use a threaded hub to secure the wheel to the hub, but pegs to provide drive (if you look at a Dunlop wheel, it looks like it has five lug nuts). The nice thing is, no splines to wear out.
An even rarer type would be the Rudge knock-off disc wheels as found on certain Mercedes racing cars of the fifties, and were optional on the SL. These were a true splined knock off with ally rims. I have no idea if they're still being made, but knowing Mercedes, they probably are, at a price.
If you know of a wheel maker, a set of vented disc wheels in the appropriate size could conceiveably be fitted with splined centers.
-William