They're essentially just as good as each other once you mod them
AU motors are better to start with if you don't intend swapping the heads, manifolds, etc. I'm chucking some AU heads & manifolds on my EB soon :D I would've gone for some better heads (AFRs maybe) but I'm not looking at having a hot NA car, so AU goodies will be definitely up to the task
HO manifold & E7 heads suck!
-Dave-