I don't think the 318 heads are necessarily bad, it seems they flow better than a lot of Fords 302 heads but 5.9l/360 heads are just gonna give you a big jump in power, other than throwing a cam 4bbl exhaust on a running 318, I don't know why people insist on running 318 heads when looking for power. I bet if all LA 318s came factory with 360 heads since the early 70's people would have a way different view on 318 performance potential.