matlowth, I am told they will fit rb30 motors using 40thou bearing machined down to suit the rb30 crank.
From what my engine builder tells me, only certain Chev rods are suited for this appiication. The big end is too wide (>86mm) to fit in the RB30's bore, so small amount of meat has to be machined away from around the rod bolts. On some rods this wouldn't leave enough metal for the bolts to hook into, on others its fine.
These rods are made from 4340 steel, magnafluxed, sonic tested, x-rayed, heat treated, stress relieved, have bronze bushings and were $500 for the set. Compared to $800 to shot peen and ARP rob bolt my factory rods, I thought these new rods were a slightly better deal.