MGA,
Welcome to the CAC. Sound like you are in the middle of a fun project.
I am pretty sure you should be able to put that half shaft back in without taking anything else out. The trick is in how you line up the diff side yokes and the wheel as you finger start and tighten the retaining bolts. At first it won't look like it is going to fit, but keep turning the yoke and the shaft until you find the sweet spot. Not a bad idea to put some tape or a rubber band around the U-joint to keep the bearing cap from falling off until you can get it into place. I have done this by myself several times (never on an 81) but find it best to have a helper to turn the wheel and or hand stuff to me when I get it just where I want it.
Sometimes the biggest pain is the exhaust pipes on the C3. The last one I did was getting new exhaust anyway, so I removed it at the CATS. I was also dropping the entire diff so anything I could get out of the way helped.
So, did you have some kind of bearing failure, or just routine care? If a failure, what kind of symptoms were you having?