Changing the rear quarters on my Dart conv. from a 69 to a 70

I have a 69 convertible that I want to make into a 1970. Changing the front group is easy but doing the rear quarters will be a bit of a challenge. If anyone has done this and can post any pictures taken during the process so I can get any ideas on how to tackle the problem of where to splice the quarters, that would be helpful on how to proceed. I have everything from the rear of a 1970 that I had parted many years ago.