I haven't looked closely at the EFI models but it seems that the biggest difference would be in the intake and/or heads. There might be a different pickup used with the EFI ECU too.
So, what is the biggest difference between the EFI heads and the carbed heads? Is it more with the intake? Do the EFI heads have a better flow? Do they use something similar to a throttle-body fuel injection?
Unless the guys doing your big bore kit are doing the head too, you might just bolt the 790 06 head onto the 09 engine... but you may not want to go to that much trouble.
