The wheels and knock offs are aluminum.
In the current Hot Rod magazine they have article on gassers and what makes them period correct. They mention something on the original Halibrands and the way to tell if they are from the late 50's is that the rim thickness is .500" vs .750" on the later ones. The DOT requred all wheels to be 3/4" for safety standards.
I will have to post some pics of the car if I get to my friends this weekend. I was there two weeks ago and the chassis was a roller and he just put the body on last weekend.