Hi Joe:
Like most things in life, one makes tradeoffs and these situations are no exceptions,....
The early SC heads had larger ports (all used the same valves) than yours and the small-port ones were optimized for more bottom-end and mid-range HP. One can use the early heads for better pulling power above 5500 RPM and in fact, those large-port heads (as well as Carrera ones) will support up to about 330 HP.
You can use a 964 or 20/21 cams for improved mid-range and upper-end power, too.
Since you have carbs, I would install the larger port heads and make sure your intake manifolds match the ports,........
For what you are doing, I don't think you'll notice any lack of low-RPM torque and it will pull hard to 6500 with the right camshaft selection (and carb configuration).
Hope this helps,