Hi Larry good to see you here. Your 59 head castings with some porting ($200) will be fine for now if the Edel's are not in the budget. As I remember the 391 was a fairly low compression engine with a lot of torque. But adding the 59 5752143 heads with smaller chambers bumped this up a bit. You can use the steel shim head gaskets as well to help a bit. The Edelbrock RPM package is a good one and I would not use the std performer package. You want more top end power and the RPM will give you this. Add the heads later and you still have a nice running package that's well matched. As we discussed just match the springs to the cam. I would not fuss to much with the heads you have if you want to upgrade to the Edelbrock's later. To completly redo them the right way you will be close to the price of the Edelbrocks by the time your finished. JMO, G.