yes, swapping heads would be an expensive experiment. You could size the intake port cross section with the formulas I mentioned in previous post...then if there is a big change in cross section you could make a new intake manifold with the new cross section...and give it a try. As mentioned, this 'bandaid' fix might offer improvements without replacing the heads... positive results would tell you which way to go for future head purchases.
Also the camshaft is 15 years old, todays new ramp profiles could make more power in this kind of engine?? Its not even an custom camshaft.
As you say, consider researching modern cam profiles. Call Lunati tech, or email them...see what they recommend. The faster rate of valve opening will of course be harder on your valve train parts. Consider switching to beehive springs with the corresponding smaller valve sprinig retainers. Smokey Yunick said to reduce the weight on the valve side of the rocker arm...the rocker arm and pushrod/lifters don't make so much difference...of course that was before roller cams with those heavy lifters.
I believe Speedtalk forum said want intake valve diameter 52% of cylinder bore diameter, and remainder can fit whatever maximum exhaust valve will work. There are also simple formulas for sizing the intake and exhaust port throat area just below the valve seat as a ratio of the valve diameter. With the throat sized, then the intake port minimum cross section and short turn cross section can be sized. They said doing this helps put off or stop intake port stalling as rpm increases.
Did you unshroud the valves by opening up the combustion chamber to .05-0.10 inch less than the head gasket bore diameter??? Did you put a 30 degree back cut on the intake valve to help flow past the valve head?? Did you take the exhaust valve margin (parallel to valve stem) and turn it into a radius toward the combustion chamber side of the valve to reduce heat build up of the right angle corners of the valve that are exposed to combustion chamber heat? Are you using rubber umbrella exhaust valve seals...or no seal at all would be fine. Heat transfer from the exh valve stem into the guide is one of the primary methods to remove heat from the valve. If you can avoid detonation that will go along way toward keeping the bottom end together of course.
How about exhaust header collector length...have you experimented with trying different lengths?
Your seems to leave the line smoothly...they say that is the best way to leave the line...nice and smooth. Could you make your own fiberglass front end fenders, hood, and bumper? How about plexiglass door and rear quarter glass to save weight similar to the superstock darts from the factory. I assume your battery is in the trunk, and extra big for more weight over the rear tires...
Great looking classic Mopar by the way.
