You will want to use crank, rods and pistons out of the 1Y engine - they are very strong and I would choose them over AAZ ones if I wanted to make power. You should also use the 1Y inlet manifold (flows tons better than the AAZ one ) - it can be used in conjunction with the AAZ exhaust manifold.
The 1Y also has an oil baffle, which is nice, and the cyl. head is basically the same. Just swap the injection pump and exhaust manifold and that's it pretty much. ( Oh and the AAZ oil pan which has the oil return bung on it ).