What parts to hang onto?

Howdy folks,
My build is "nearly done", don't know if I will ever be able to say "finished". I have a good many parts left over as I went through 3 parts cars and several junk yard trips to get to this stage.
I want to clean up my shop and yard of these extra parts, but wondering what I might should hang onto, that might come in handy or that is not so readily available aftermarket yet. I am not so interested in parts I can get every day at Auto Zone, or big sheet metal parts that is repopped. After reading a post the other day, I might want to keep a set of the torsion bar adjusting bolt & nut. Things like emblems, spare tail lights, that sort of thing. FWIW, this is a '72 Duster.
Thanks for your thoughts,
C