A comprehensive book on engineering, a comprehensive book on gunsmithing, and a comprehensive book on chemistry. I carry the formulae for gunpowder (black and smokeless varieties) in my back pocket at all times, so it is part of the clothes on my back. My goal would be to first establish a private army armed with advanced weapons; second to establish an empire over Eurasia by 762; stamp out all traces of Islam by 782. I would also assume both the Papacy and the throne of the Byzantine empire, and in doing so establish permanently a united Christian faith all across the lands I ruled. I would be corrupted by the power I wielded, ruling by force and terror, and eventually be overthrown by my subjects, who would then fight amongst themselves and destroy civilization. No doubt I would have an interesting paragraph in a history textbook. Perhaps I would even be regarded by revisionist historians as a great humanitarian because of the wonders of technology.
LOL, best so far.