The Triumph has wide pistons. This means the flame front has a long distance to travel. The rods are short in comparison to the stroke. This causes the piston to quickly move away from TDC. A fast burning gasoline is needed to make the flame front move the needed distance in the very short time that is available. This is something I knew about and I run a flashy and light specific gravity leaded gasoline. It works very well. The combustion peak pressure is likely to occur in the desired 14 to 18 degree ATDC range.
The jungle juice is mainly this gasoline with some other goodies. One is a highly volatile compound containing nitrogen, hydrogen, and some oxygen. My suspicion is this is flashing off early and peak pressure is happening before 14 degrees. This puts large stresses on the engine like the ones I am seeing.
This year seven ignition modules will be used in the dyno work with 8, 6, 4, 2, and no retard, and two more with 2 and 4 degrees advance. The objective is to get a better idea of the peak torque vs spark advance relationship with the juice. The engine will tell me the curves it likes best by the dyno results. Then, I just need to pick the most retarded curve that provides decent power. This is something I always did, although I never had enough modules to give me a good curve. This curve analysis might be especially critical with the juice.
I was going to do all sorts of expensive strengthening of the lower end. That might be treating a symptom rather than fixing the causative problem.