I had the same issue with my '67 Barracuda. The factory swaged the lug studs just outside of the drums, which holds the drum to the hub. I was told they did this to aid in assembly as the could install the drums and hubs in one assembly. On mine, I was able to lay the drum on my work bench and drive the hub out of the drum. Heat might help with this, but it likely isn't an issue with the hub being in the center hole of the drum, rather it is tight where the studs come through the drum.
I've heard of a couple of ways to deal with this so you don't have to mess with it in the future. One suggestion is to grind or file the swaged areas on the studs. Another way that someone suggested is to get a hole saw with an inside diameter that matches the outside diameter of the studs (7/16" I believe) and use the hole saw to cut the swages on the studs off. Another method is to drill out the stud holes in the drum slightly so they will clear the swages on the studs.
In my experience,... those hubs are hard to find, so you will want to find a way to save them!
