Have you done any work to the head and intake manifold? The engine could do with a tidy up on the intake ports and port matching, rework of the valve bowls to make them similar in volume and gas flow, radius and blend sharp edges in the combustion chambers - and a set of wrapped headers. These engines respond to well to a more aggressive ignition tune too. How do you manage ignition advance with EDIS?
I haven't been keeping up with your posts so if you do have a write up on your IGN set up, it would be cool to check it out