Back in the early sixties(1962) I helped a guy start an 406 install-----he got transferred to the west coast and I don't know if he ever finished it----the Y block engines exhaust manifolds came up and over from the ports where the FE manifolds went down and back---car was very narrow in that area at the side of block but towards the front of engine was some room altho then he had to go down/back where as stock went down from back of heads near bellhousing---

also might be problem with oil filter location---------