That's one big n chunky root, can ya weigh it and count the neck scares? It would be nice to know the age and weight!It looks like it is around twenty or so years old but the necks not in focus for a accurate count.Fits with your grampa's plantings eh?
From the picture,selling it dry may be an advantage.It appears to have nematode damage,that is the small balls on the fine roots. You should dry it and remove all evidence of the infection and put it in with your normal sang for the best price.
Guy