Your best bet would be to call the manufacturers. But remember that you start compromising strength with some super lightweight wheels. I recall a center breaking out of a wheel when a car turned a corner past the ticket booth at Norwalk years ago (Rink/GTO/Nova???) and an early Camaro leaking air in the staging lanes at Dinwiddie from a stress crack.
Holeshot Wheels has a wide variety of styles which are pretty light and with custom offsets. They have also started producing lighter one piece billet fronts which will eventually be available in all of their styles. But you'll need to call for specific weights.
www.holeshotwheels.com