I don't know what you are asking,,,,,,AGAIN.
A pro mac 81e is probably the best 80cc motor mac ever built, I know of one that races here and is still very competitive. I also seem to remember that it is a piston ported motor, one of the few big saws that mac built without reeds. It also had electronic ignition, something else that was rare in a big McCulloch.
I haven't messed with the cart motor, but I think its close to a super 250/300 reed motor in design. More torque, less RPM.
I would take the 81E if given the choice.