If you want an RV that is LSA compliant, then an RV-12 is probably your best choice. Register it as ELSA or experimental, whichever you prefer. You can shoehorn an RV-9 (or even a 7 I believe) onto the RAAus register with a 600kg weight limit, but not easily (and maybe not anymore these days either?), and certainly not without some compromise in speed and/or payload. The current RV-12 kits give you a choice of ULS or iS engines. Vans say the iS is significantly more fuel-efficient than the ULS (30% or more).