If I had the money, I would buy an old NASCAR engine. They are proven bulletproof over 750hp and 9k+ rpm. I have seen a rebuilt Nationwide engine detuned by cam and compression in a street Camaro with pretty good results. That is state of the art for that type engine and can be had at a price probably less than those heads and a block.
Most teams will sell outdated (like last season) engines at a reasonable price for what you get.