Demon front end conversion. INPUT??

Hi,

I'm new here so forgive me on the lack of A-body background (I am more of a C-body fan, I have a '69 T&C and a '69 300 convertible). Anyway, I bought my daughter a '75 Swinger that we are trying to fix up. I would like to do the same conversion that I was reading about here but got confused! I looked through lots of photos of the front fenders of these cars and realize that there are two types of fenders. Those short fenders with the extensions, and the full fenders that go all the way to the headlights. I thought that this was due to the year, but then I saw a '71 Plymouth with what looked like the same fender of the '75 Dart Swinger?

So, I need to get this straight, do I need to replace the fenders if I were to put a 71 or '72 Plymouth hood, bumper, valance, and grill on?

Thanks