Ok, now my interest is piqued too. I haved a T85 with the R11 gears and I am wondering what I am going to use for a shifter. I have an old NOS hurst shifter, I will have to get out that box and see what it says. If I remember correctly, it does say 55-56 Fords, but nothing about overdrive.
Richard - I would say that with that shifter arm, there is NO way that you are going to clear. Seems to me that I remember that a few years back Hoosier Hurricane posted some photos of a good setup that he had, or one that he had seen. There was a nice "Z" in the arm to clear the bench when you went all the way back like that last photo you have there.
Have you taken any measurements on the wagon's body?
Daniel JessupLancaster, California
aka "The Hot Rod Reverend" 
check out the 1955 Ford Fairlane build at www.hotrodreverend.com