OEM 340/360 rod in a 408 stroker...??

$150 with arp bolts is what it costs around here to redo some 340 rods.

Stock floating pin 340 rods are good for a 500 hp 408 no problem, after 540hp it's a crap shoot, but depends on the build.
But really those rods are good for 8000rpm if done right.
I've turned mine 7000+ rpm many times.
A good friend of mine turned his 8000rpm even touching 9000rpm in circle track racing back in the day at el cajon speed way.