Well, the 15 inch spoked wheels weigh about 8.5 Kg without tires, which is actually ok. the center lock hub is even lighter than the 5-sharred hub. Everything was weighed at my workshop when I was looking for alternatives for my then Plus4SS 11 years ago because the Minilite plus hub adapter weighed over 12 Kg without tires. I had a Roadster with the 16 inch stainless steel spoked wheels, and they were weighed as well. I remember (not exactly) that it was more than 11 kg without tyres.
In principle, however, a solution with hub adapter is heavy. So...because a hub conversion is very expensive, and because the cars with spoked wheels could have wider fenders I would stick with the original alloy wheels.