how much money do you wanna spend and how much power do you wanna make? for a mild 347 you could go with some afr185s or performer rpms or some twisted wedge heads. those heads should make around 350 rwhp with a good custom cam. if you want more power, get a trickflow r heads and intake or afr 205s or the vic jr heads from edelbrock. you can make over 400rwhp with just about any of those heads and a good custom cam.