3 point seat belts in 68 dart

I would like to put in 3 point seat belts in my 68 dart just for some added protection. I have the stock shoulder belt that mounts to the roof but its really uncomfortable. Has anyone taken the 3 point belts from a late model dart and used them in a 67-9 dart? Does the reel get in the way of the door & seat? Options and pics would be great. Thanks...