Will, Phil,
Been reading the thread with a bit of interest. I'm neither a degree'd engineer nor a metallurgist, but I think there should be some consideration given to any upward thrust of the piston/rod assembly applied against the rod cap that may occur anywhere within the 4 cycles.

When the piston/rod assembly is within the last 90 deg of the exhaust stroke and the first 90 deg of the intake stroke there is significant deceleration and opposite acceleration at play. Something has to keep the piston and rod from continuing right out through the head. And when the crank starts pulling the p/r assembly downward for the first half of the intake stroke there is continued load against the rod cap.

So the question - is this upward load against the rod cap significant enough to warrant all the fuss over bolt strength? It might be. Someone smarter than I would have to calc all that piston/rod/wrist pin mass times stroke length times acceleration......