Hi Gary,
I'm not sure about your '50's rear brake construction, but I had a similar experience with the Roadmonster. So, I am assuming that the rear wheels/tires on your car are
BOLTED on, rather than putting NUTS on studs. This assumes that the drum does
NOT have studs and does
NOT have a center big ole slip-on taper with a 2" or so nut on it. Right? (If your drums do have a big old taper-fit hub and big ole center nut, you'll be buying or renting a tool. But have no fear--the tool actually works.)
If so, here'a a couple of thoughts based on my Monster.
1. Look on the face of the drum for a 1/4" or so bolt (7/16" head) on the face of the drum, ie, where it would be against the back side of the wheel. It might be a slotted screw head--who knows? This (these) bolt(s) may or may not be there. It (they) holds and aligns the drum on to the hub when the tire and wheel are off. As I recall, there could be three of them.
2. There should be one, and possibly up to three, pointy studs, or pins, about an inch and a half long and 1/4" - 5/16" diameter, that are screwed into the outside face of the drum just like the bolt(s) I mentioned about. They stick out through the small holes in the wheel. They have a hex-head at the base for a wrench to grip upon for removal. These are what GM laughingly supplied to guide and support the spare wheel as you wrestle around in the mud (It ALWAYS is raining when you have to install the spare) trying to install the wheel bolts. Past owners may have yanked the aforementioned bolts and installed multiple pins in the bolt holes to try to support the loose wheel and tire as you attempt to install the lug bolts. I know that I did just that, but then I made a set of heavy duty guides that actually work.
Whether pins or bolts, they will prevent the drum from coming off. They unscrew easily. This should make it possible to remove the drum.
If the drum is surface-rusted on to the hub, there is a puller made for the problem, though ususally some PB Blaster and some tap-hammering with a heavy hammer will break them loose. I have had occasion to use this type of puller (modern Chevy trucks require it). But first check out the above pins/bolts in the face of the drum and see if that resolves the issue.
For future reference, when installing a wheel and tire it's always a pain to try to hold the heavy wheel and tire as you attempt to get lug bolts into place. One solution is to have a set of heavy-duty guides that you put into the lug bolt holes to wholly support and hold the spare in place as you start three of the lug bolts. Then you remove the guides and install the remaining lug bolts. I make those guides if you want a set: $19.00 a set plus postage. Just keep them in the trunk for when the occasion arises.
Let us know how this works out.
--Tom