Charlie, When you have a chance, check the back of the block and see if there is a letter C scractched in the block..
Then check this website. They have a pretty good handle on the spread of Ford part numbers over the years.
http://www.mustangtek.com/block/Block.html
You run the list on the left side of the page and you can trace about anything you need to from blocks, heads, intakes, and many more.