I wouldn't bother with after market rods unless going h beam, I have many sets of floating 340 rods and arp bolts that would save $$$ and work great to this level of hp, but thats me.
I think you're right about handling the horsepower but the generel consensus seems to be that the cost of reworking stock rods & adding the ARP bolts is about the same as buying the aftermarket rods. I'm not sure if just adding the bolts to the stock rod is all that's necessary to make them clear the block with a 4" stroke but the aftermarket I-beams usually clear without grinding on the block.