You don't have to worry about the galvinized metal, because the asbestos kept it from burning.Asbestos was a popular heat insulater in those days. I don't guess we'll ever know how well these cookers worked back then, because everyone who built and used it are All Dead!!
I also recommend applying a few coats of lead based paint and letting your kids nibble on the paint till it starts to chip off.
Look at the pic......that dude's a 50's stud. Has his wife, mistress, and mom over for a cook out. Pair of brass cojones on that dude! Or maybe it's his wife, mistress, and his cougar. :twisted: