What lens should i use to make a tilt shift lens for my Nikon fg?

I'm not sure what i need, i have heard medium format is ideal, but is that the same as a normal lens with more than 70mm of focal length?

Added (1). When i said normal lens i meant a 35mm lens, so i what i really wanted to know is if i can use a lens that isn't medium format and has more than 70mm of focal length?

You are making your own tilt-and-shift lens? The closest thing I have is the Lens-in-a-Cap.

Medium format refers to 120 film. Normal lens in medium format is around 80mm.

In 135 film or 35mm film, normal lens is 50mm (or around 40mm to 58mm).

Check out the tilt-and-shift lenses here.http://www.bhphotovideo.com/c/search?Ntt=tilt+shift&ci=15293&N=4294205295&cm_sp=Filters-_-Category-_-Photography

For Nikon, here's what I found.http://shop.ebay.com/i.html?_from=R40&_trksid=p5197.m570.l1313&_nkw=tilt+shift+nikon&_sacat=See-All-Categories