<<So, perhaps the stretch bolts themselves are not the problem, but
excessive bearing wear is the true culprit.  That means scrupulous
attention to maintenance coupled with careful oil pressure monitoring is
the key to longevity for this engine, just as it is for any other.
>>

The reduction of bearing wear is one of the main reasons, among others that I chose to have the crank counter-weighted.

In T1 engines with noncounterweighted cranks the case pounds out instead the bearing as much.   When the T1 engines have the power increased, the case can be worn out in little as 50,000 miles OR less.  In the WBX engine, the case does not pound out BUT the bearings wear out quicker and sooner the harder the engine is pushed.

If you rebuild and have time, get the crank counterweighted.

Robert