I am led to believe whilst torque can obviosly kill a rod it is far more likely to be revs, failure occuring at the top of the exhaust stroke! As it has no force pushing down on the piston.

I spent alot of time with Harvey Gibbs sorting a spec for a silver top and he reckons with ARP bolts they are good for 290bhp as per a couple of engines he has done with no failures!