the right heads!

If heads are not a priority and money is tight, I wouldn't even think about the W2s or W5s (which are aluminum heads). The cast iron W2s are still going to be costly and you can multiply the cost for the W5s x2 if you want them to work to full capacity. Even the cast iron Econo W2s will work probably work the same as the heads you all ready have (since thy have been somewhat ported all ready). Just stick with what you have and go after all the other stuff you mentioned that the car needs.