I know this may be more info than you care/need to know, but NASCAR engines at that time were based on a 351 Windsor style of block and intake but utilized 351C-based, canted valve cylinder heads. The cylinder heads in this kit represent raised port Yates heads, as can be seen by the extra detail on the exhaust side. As Brian said, the rectangular valve covers, with eight bolts is a dead give away that it's a Cleveland style head, given the context of the kit. I have owned several 351C engines over the years, so felt compelled to provide a bit more info... LOL