I've seen OEM 273 rods run successfully in race applications but the ones Mopar sold through Direct Connection, including their standard size 340/360 version, were forged from 4340 material, like Scat I-beam and many H-beams rods today. Eagle SIR I-beam are made from 5140 material and I'm pretty sure OEM rods were another step down, but obviously still strong enough to take a lot of abuse.
I had a couple of sets but have been selling off my stuff. They had "Mopar" cast right into them!
Direct Connection/Mopar 273 style aftermarket rods.