There are a few differences to account for:

• The multitouch cable connector on the upper case has been relocated in the Rev.b machines, which makes connection difficult.

• The black shielding on the lower case is slightly different. This may or may not affect compatibility.

• The audio board is not compatible between models. You would need the correct audio board and cable for the appropriate logic board.

• The hard drive connector, as you noted, is different and must be worked around.

• The fan/heat sink are 2 separate pieces in Rev.b.

• The airport/bluetooth cable is slightly different as well.

I haven't actually performed the swap; these are just the physical differences.

Good luck!