Check out the different pistons, while the older version has a lighter cylinder, the piston is much heavier, 3oz vrs 2 3/4oz roughly. The piston squirt is longer and thicker, and the rod is much heavier and beefy. Wonder why the change.
Now you would think the higher ports and lighter weight piston in the newer engine would be much faster even though the intake ports are much smaller, what do you think the results are.