First off, welcome to Golden Age Comics!!! You picked a great title to start collecting! This IS the last issue of the run and it's loaded with John Romita artwork! To your question of finding a proper back cover for the book, you must first determine what the inside & outside of this issues back cover actually looks like and then you can set about trying to match one up. As stated above, a good place to start is an Atlas comic of the same month and year. There are likely to be some that are the exact same, but likewise some will probably be different. Once you can determine which books having a matching back cover, you can start hunting around for inexpensive, perhaps low grade or even books missing the FRONT cover to get your donor back cover. Good luck in your quest!!