An AW's an 1800 case. Don't recall the piston size offhand. They bored the 1700 to the 1800, then stroked the 1800 to 2000. At any rate, your heads have the biggest valves of the three, so keep them!
I've got one of the tools to take off the flex plate-I got it (in a set of 5) at Pep Boys or Autozone, one. As I remember, one of the sizes in the set worked for the CV joints, too. You can borrow it or hunt for one, but they might have gotten rid of them to make room for neon exhaust tips or some crap, but I digress.