The ONLY advantage to running an early block with late model heads would be that you can get a better timing chain. Currently there are no double rollers for the VVT setup.
Also, the early pistons with the smaller chamber heads and the early pistons with a slight dome would result in a very high compression ratio over 11:1. This would be too high for pump gas, but if you were building for E85 it might work. Though, I think piston to valve clearance MIGHT. Also the intake and exhaust port are shaped like the 6.1L Hemi, so changes to intake and exhaust manifolds would be in order.
The short answer to running Eagle (09 and later) heads on a 03-08 Hemi block is to build a fresh motor, choosing the right pistons and manifolds to get the best performance. Personally, I'd just buy a 09 and be done with it.
Regards,
Joe Dokes
