My thoughts are with that stage 2 68r that the upper rpm Fuel will be falling off...
With the miles your pump has, I would put a sportsman pump or (stock stroke) modded pump....won't deliver a bunch more bottom end Fuel like a 10mm would, but will Fuel harder above 3000 rpm....
That being said, do I think he needs it, probably not, but a matter of preference. But if he can hold 26,000 psi at 3000us+ duration vs 21-22,000 at same duration, it's gonna make more power!
I have a 225,000+ mile LLY customer that on a 3000us tune was only holding 21,500-22k psi... I performed my own bag of parts mods to his cp3 and ported his fuel rail fittings, and his truck would hold 25,500-26,000 on exact same tune. I performed these mods while it was tore down for head gaskets, I think the Modded Cascade valve makes the biggest difference, but that and drilling out the ports to the gear pump/lift pump. And I left his factory LLY regulator alone, and it still helped!