LO206 limited to 6,100, World Formula to approx 7,200, Animal in effect not limited (has maybe 10,000 limit). Different PVL coils control the max rpms. You can convert a LO206 to Animal by changing the PVL ignition.
World Formula is different, has different head, piston, rod, carb, cam, valve train, but same block and crank. Great engine too, but I personally like my Animal better. :thumbsup:
In terms of stock HP: LO206, then Animal, then World Formula would be the most HP.