Craig, were you able to tell if your flywheel was lightened?
Re: Engine Cases-I spoke with a former CB Performance employee back then (CB used to be Claude's Buggies). CB was one of the companies that sold Don Hatz the parts he used to build up engine cases. The VW Engine Number list on TheSamba claims all AS41 are dual relief cases-they are a later case designed to be universal fit for use from T1 to T4. This employee, Scott, told me a story how the single relief Brazil AS41 cases came to be. Gene Berg "wrote the book" so to speak, or, at least, preached a gospel that Thou shalt never line bore; thou shall always use a new engine case. It was in Gene's interest to sell engine cases. So Bob at CB disagreed with Gene, to prove his point he commissioned the foundry in Brazil to cast AS41 cases with the single oil relief port, which CB sold hundreds if not thousands for $199.95 out the door.
With the large offroad racing and VW community in California, and the numbers of engine cases CB were bringing in at a time, its possible/probably that other part number engine cases were used by Don, from dual port AS41 to the AS21 cases (AS41 were made witha 4% magnesium 1% silicon alloy; AS21 were made with a 2% magnesium 1% silicon alloy) or even used engine cases if Don felt he could safely build them.