To me, the best tribute would be a journal of your father's recollections about him owning and enjoying the car. - And some pics (then and now) thrown in for good measure. You could also include receipts and original dealer paperwork. If you don't have any check with the state's DMV - they usually archive that stuff and can get it for a small fee.
The glovebox is cool but would hold most value for you, your dad and family. The next owner would probably change it out - they'd keep the signed one but change it for a non-signed one. If you plan on keeping - do what you want.
It is really neat that you have a car your dad bought new!!!!!!
Ray