Yikes! I'm gonna be dreaming about those boxes and their contents for the next few weeks. I'm absolutely not complaining, I'm just wishing I had the opportunity to run my fingers through some cache like that. Holy crap, that is some kinda great coinage and currency. The stuff of which dreams are made (and seldom realized).
Girlfriend's grandpa should be even more appreciated now, and for the remainder of his long and healthy life, for his foresight and generosity. The man is my newest hero!!! Ah, the elderly, truly our "treasure" and the one most often overlooked. Ask grandpa if he remembers the locations of any outdoor dance floors or picnic grounds or ballfields or any other place people may have lost coins long ago. Then do your research. I'm telling you, grandpa may be a true "gold mine" of information. Give it a try, it probably can't hurt him or you and gf.