I have done this many times. From 70 to 75 and from 74 to 70.
You have to change the hood, grille,bumper, and bumper brackets, both front fenders, and that piece widt the hood lock. In other words, you must change all the parts from your doors an forward.
Its all more or less to bolt rigt on. Maybe you have to drill a hole or two, but thats it.
Sorry for my not so good english, i'm from Norway..... **(*)
Here is my old 70 Swinger. (yeah, a four door Swinger)

With 75 front end.
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