Not with a 408 Stroker pushing over 450 HP.
I have a Mike McCoy here in Lehi, UT whose been building rearends and transmissions for over 30 years tell me the same thing, he told me about 350HP & below is what he calls "safe" for a stock sure-grip 8 1/4.
Plus, I already have all the parts minus the ring & pinion to assemble an 8 3/4.