Interesting numbers. Thanks.

Looks to me like the biggest change from your old motor is that Sam got rid of a hole in your torque and HP curves (5200-6000 rpm). If you hadn't had that, the old motor wasn't really that far off the new one - and probably ahead from about 5800- 6400. (assuming the FW/RW conversion is correct)

Did Sam mention anything specific on the carburetion that might account for the hole?