Where can I get an old xerox copyflo drum model number 914?

The 914 drum is a photoreceptor drum for the Xerox 914, the first fully automatic plain paper copier. The machine has not been made or maintained for decades. You would probably have to go to a technology museum to find one, although you might ask whether the Xerox Historical Archive, at Xerox Corporation in Webster, NY, might have an extra they can spare.