Lepape's move in the Jug was a vertical snap roll which is what initiates the Lomcevak. Neil Williams has written that Bezak, the originator, told him there are 5 basic Lomcevaks, all with variations. The Main, Cap, Positive Conic, Negative Conic, and Tumble. As Mace noted, we don't have the torque for the tumble but I believe Lepape was arguably doing variations of the Main and the Cap. I believe you can do the Positive Conic in a P-51 with a negative snap roll in a vertical zoom climb. Williams mentioned flying backards while climbing in a Lomcevak and I've previously posted a picture of that in an F4U.