As said I would get some 68-70 HP ex manifolds & dynamax (sp) turbo muffs with in addition glasspacks alongside the rear leafs. those Aeroquip heads are a mass produced item & there have been bad reports (but the internet is the complaint dept so we do get the bad experiences, just sayin). Are your current heads OK? if so I would leave em be & possibly swap the cam (what is your SCR) & get a good torque converter. Some aluminum stealths might be a cost wise alternative (again what shape are your current heads) & you might eventually get a 400 block/440 crank for 451 cubes!. when done be sure to dial in your dist subsystems in order. EDIT Mandrel bends 2&1/2" system/X pipe.