So, it has been a while since I've opened one, and mine is the later version, but, I think that the two side screws that hold the distributor cap in place, will let the breaker plate assembly out of the distributor housing.
As always, if you happen to pull the distributor housing up from the block when rotating it, assume that you have disengaged the distributor tang from the oil pump slot, and the engine lost lubrication. It is hard to see the housing position with the fenderwell on. Don't assume that the oil pump is spinning after tinkering around with the distributor clamp. Check back with Mud if you need help seating a distributor. Motors on other vehicles were engineered so that the oil pump is spun by the camshaft, making the distributor much easier to service by the novice and shade-tree type mechanics.
Just a tip. I've found it to be important that when you are working on neglected motors, you pull the plug, scrape the oily soil from the outside of the head, vacuum out and q-tip the junk. Then dip your plug in gasoline and use the plug to clean the threads on the head by installing it, removing it, cleaning it with a wire toothbrush, then repeat to get the plug to install with just the socket and an extension, aside from achieving the actual torque with a ratchet. This allows for quick inspection / plug reading, and it insures that the plug is seated with the proper torque.