I'm guessing I'm looking at a stock MustangII in an AD. I have an aftermarket MII (Progressive) in my 52. I don't know what engine you plan on, but my orignal plan was a small-block, even though I wound up with a straight six. The motor mount position was the same for both, and it appears to be about 6" back of where yours is. I would suggest you get a cherry picker and trial fit the engine. Moving the mount is easy and you might even consider the tubular crossmember that is readily available for V8 swap. If that is where the mount has to be, a little fancier bracket bending for the mount, properly gusseted, and perhaps with a through pipe for the steering shaft and you're in business.

http://www.homestead.com/chuckthetruck/files/xEanq_022.jpg

http://www.homestead.com/chuckthetruck/files/ex2.JPG

http://www.chuckthetruck.com