There are many ok, fair and even good OEM heads available. Unfortunately, these that you have are not. 351cid D0OE-C/G, GT40Ps from Expolrer's and Expeditions to name a couple are pretty good. Then you get into a bazillion or so after market iron and aluminum heads that start fairly inexpensively and go up from there. It all depends on what you want to do with the car in the end and how many $$ you have to get to that point.