I saw the same add man! I am currently balls deep in rebuilding my RB25 head. It isn't very difficult to change out valves, but it IS time consuming and gets pricey. (could be hard if you don't have all the tools and machining equipment too.)
I would say just be patient. There is bound to be another s13RB monster popping up on here or on other sites that runs well and doesn't need any work!
OOOOR you could sell that RX7 and build one the way YOU want it
