360 vs 408

I'd personally be fine with stock rods and hypers for the present stock stroke build plan. Forged are tougher than hypers when you get into detonation but run looser, and I've destroyed forged with detonation, and raced a trubo'd engine a 14-15 psi with both hypers and forged in it with no problems with either. So it's all OK if you use good tuning and care, IMHO. I'd upgrade rods before the pistons... just my take on these things.

With Magnum block milled perhaps .005", those KB107's will stick out around .008". So make sure you use a thick enough head gasket's Felpro 1008's would be getting the pistons clearance from the heads almost down to .030", so I'd be inclined to use the thicker 8553 PT's and push it up around .040".

Making an educated guess on the cam's intake closing angle (Hughes never gives you that info), I am getting 7.9 for DCR so that seems all OK.