i've run several 400's from stock blocks with stock cranks to brodix aluminum blocks with callies cranks and oliver rods and with the short rod and fast piston speed at top dead center you can't go wrong with an aluminum head with 180 to 190 cc port volume as it will keep the port velocity up and more efficiently fill the cylinders. you can use a cam with 230to 240 duration @.050 and be very streetable on pump gas also with the aluminum head you can run 10 to 10.2 or so compression without detonation and if you buy a head(i'd run airflow or brodix) with smaller combustion chambers you can always run thicker copper head gaskets to lower the compression ratio... hope this helps