from Northeast Pennsylvania I can't help you with the parts you need but try posting in the Classifieds under "parts wanted". I'm sure someone can help you. The gas tank might be easy to find but a good dash pad is a slight bit rarer.
welcome to the boards The classifieds should help with what your looking for they've helped me find what I needed. if not someone might know if there is one that interchanges
Welcome aboard! You can buy a new tank for the 74-up Mavericks. It's a larger tank and you would have to either use the correct straps or just longer bolts. There are several people that have made this swap. The dash pads usually for for $300 or so for a nice used one. You can install a dash cap (hard to tell diff from factory dash) for less than $100. You can do a search on both of these items. Been discussed many many times.