Well Ed, I would say it would depend on how much you want to spend, haha. Items that have been rolled for decades are difficult to relax as the paper fibers have stiffened and dried and are easily prone to cracking. The best route for it would be to send it to a paper/poster conservator and have it linen backed and cleaned. They could even paint in any missing areas if you wanted it fully restored. Obviously this will cost more than it's worth more than likely. Having a custom frame made and using an acid free backing would probably be the most economical route. The banner could be left basically as is and being pressed between the glass and the backer would prevent any further paper loss for the most part. For some of the most fragile cracks/creases that are in danger of separating, I use acid free tapes in some of my ephemera restorations and I would be apt to use them in this case to prevent those areas from fully separating. It MUST be an acid free archival tape in order to not damage it more in the future. I'm sure everyone has seen what old magic tape and masking tape can do over time. It causes darkening and damage from the acids in the adhesives, and is very difficult to reverse. Some acidic tapes turn gooey and super sticky over time, others dry out and leave a permanent residue. I like that this banner has the NRA logo, which makes it very easy to date. I have an NRA cardboard window sign hanging in my living room. It was a beautiful logo, albeit a short lived depression era program as it was ruled unconstitutional by the Supreme Court. There isn't much out there old gas related with the "blue eagle" logo on it.
Darin