Stock Magnum rods/pistons durability ?
My first 5.9 build was a junkyard 2001 motor with abouta100k miles on it. i just had it cleaned, crank polished, honed and new cam bearings installed. I rebuilt it with the same pistons and rods, didn't touch the rod bolts (I know, everybody says that's a no-no) or anything. New rings and bearings, and a regrind on the cam. Took my time assembling it. Motor eventually got a turbo and was probably pushing close to 550hp when I finally broke a ring land on one piston from probably a lean condition under heavy boost. Rods, crank and cylinder walls still look good after tear down. Bearings were worn from lots of boost pressure but aside from that everything looked good.
I bought another JY 94 5.9 with a ton more mileage and started down the same path. Dropped it off at the machine shop and my guy said the cylinder bores were great. So, polished the crank, honed cylinder walls and stabbed new cam bearings in it. I'll probably go with forged pistons and rods this time due to my HP goals but the Magnums are pretty stout (at least in my limited experience) using the factory parts.