Changing the rear flange was my first thought, but the universal joints are different sizes between the two tailshafts that I have. Then my next thought was to get the tailshafts cut and swapped, ie make 1 useable one out of the two I have, but I was quoted at $220 to have that done. Which I really didn't want to pay considering I can get a T series for cheaper than that (hopefully).
I'll be getting stuck into this car again when I get back to Byron, I think I'll have the engine running in a couple of days. Then I'll sort out the tailshaft.