$700 for a ported big valve head is not an awful deal by any standard. Particularly if you want to keep a stock appearance. And yes, you can use any rocker assembly you want. They all interchange on this engine.
However, it still has the 1 barrel carb mount, and that has to be converted for a direct mount two barrel or a triple carb setup in order to break into any serious performance. Either way, an additional expense which will run the price up well over $1000. At that point you are getting pretty darn close to the aluminum head cost, but nowhere near the potential. The cost/benefit ratio starts to head the wrong way really quickly on the stock style heads.