need help on dash

Hi There, new to forum. I have a 1970 Dodge Dart Swinger and want to put different dash and gauges in it like the ones from fast lane.http://fastlanewest.com/store/index.php?main_page=index&cPath=21_206 But these say 71 to76 can anybody tell me why they wont fit. I called them and they said they do not make them for 70. My gauges are the long narrow ones, But the dash is more or less the same style. Can anybody help me?