Bentley, this is what a Ford friend of mine said when I asked him:
“The part number is from a 1960 model. From my research it looks like they were used on 1960 352’s and 1961-62 390’s. They are considered some of the better stock FE Heads because they have good valve and port sizing and smaller combustion chambers for better compression. I’ve seen bare sets on eBay ranging from $950-1,800 a pair. (Upper end being NOS)”
Hope that helps you and that all is good up North. Keep that survivor in sweet shape and stay classy
