wah, while i am out of commission so many nice discussions. have to get new modem. suprisingly, opera mini on mobile phone works quite well with zth.
Ok, now back on pc, lengthier reply now possible.
One thing about big stroke bad for rpm is cylinder bore sidewall loading.. the more severe, the worse the piston pushes on the wall at the bottom of the stroke.
The mat salleh does 9K with 89mm cranks by running good clearances on the bearings, which is why they plastigage everything when they mount the crank and crank bearings, and correct by polishing and bearing sizes.
One or two 'looser' bearings might be okay for normal rpm, but at very high revs, expect a lot of vibration. Something I believe causes some B20B blocks to prematurely fail is something call destructive resonance, due to the crank vibrating on the block.
But overall, the B series stock cranks and rods are quite sturdy, and can push higher rpm, but when people don't bother about crank bearing clearances, I guess it's natural that some blocks fail and some don't.