what is that engine out of then usually? Speaking of auto's, i'm one of the unfortunate few that has the auto box in an aw11. Honestly, they should have never fitted the 4age with an auto, it just sucks balls, so i can see why you need a bigger engine
If it's smaller i don't see why it shouldn't fit, but i think your best bet is to measure an actual engine to see where you're at, and get a better idea of the dimensions