I've been looking around for some closed chamber heads for my 454. My brother in law has a set of oval ports. 65-66 396. casting # 3872702. I checked on mortec, but thats all the info they have. I need to know the valve size, so i can figure out If i can even use these heads or if I'm stuck looking for 67 3904390, or 68-69 3931063 heads . It's a low compression engine now. 7.75-1. The early heads closed chamber heads would bump me up to 8.5-1. I would just buy new heads, but they are all 119 cc chambers.