Before all the good aftermarket aluminum heads came out, we used to run the early '69 to '71 351 W heads. Due to CRS, I can't remember the casting numbers but I do remember with some mild match porting they performed very well. Maybe some of the Ford guys can help you with the numbers. I might even have a set around someplace if I dig deep enough in the "slightly used parts" pile.... Does anyone else have the casting numbers and specifics on these?????