I have a 69 350 4-speed with #47 heads that I had rebuilt as stock. I had a cam put in and changed it to a 4-barrel. That did not work for me. I bought a set of #48 heads that I had rebuilt. They had to fix the valve guides and finish a porting job some one had started. $1500 just for the heads and to install them. What a difference it made though! I have some #62 heads that I bought as back-up heads if you are interested in buying them. Pete