Either the RHS pro torker vortec head or a Upgraded modified GM 062 oem vortec head will work great on your 400. use either the Comp XE274H-10 or the Comp XE284H10 . It will make more power with the larger cam yet still very torky with the vortec type head.. it's not too much.
If you want aluminum, get the 64cc Edebrock E-Tec head. Use a vortec intake manifold. Either way will be a winner. All these heads are better than the Patriot heads. More usable torque thru the majority if the rpm band you'll be using..
If you have the factory type 400 dished piston your cr will not be too high with a 64cc head. If you have flat tops in your 400 use a 72-76cc head.