When I changed the clutch in my '51, I was able to remove the bellhousing after pulling the driveshaft, transmission, and transmission mount. Since the latter holds the rear of the engine up, you need to put a support (ideally a floor jack) underneath the oil pan. After everything is out, you have to lower the rear of the engine a bit to get at the top bolts holding the bellhousing to the block. You can get at them with the normal combination of sockets, extensions, and u-joints. Since there is NO removable inspection cover (the bell housing is all in one piece), it must be removed to change the clutch.
When you're done, you should consider changing the front motor mounts as well. Letting the back of the engine down enough to get at the bolts puts an unaccustomed strain on them and since they are probably old and partially deteriorated, they will suffer from the process. When I did mine, I still had clutch chatter until I replaced the front mounts.
