Good ideas but as the other site said you might be killed for being a heretic by the religious leaders of the day if you go overboard.
Actually, being killed as a heretic for technical knowledge would be vanishingly unlikely in 742. Before the 11th century, the Church, both East and West, followed the wisdom of the Fathers that the execution of heretics was a horror to be avoided — heretics needed to be silence, but they also need to be given a maximal chance of repenting — all the great heresiarchs of the Christological controversies (and the Orthodox they accused of being heretics when they had the ear of the secular authorities, cf. the treatment of St. John Chrysostom) died in exile. Likewise the belief in witchcraft was condemned as pagan superstition until about the 11th century, so it’s unlikely technical prowess, especially if one showed how it was done, would be treated as witchcraft.
(In the East these attitudes continued until they finally broke down in Russia in the 17th century — in the West, heresy as a capital offense and the belief in witchcraft seem to have been picked up from Muslim Spain in the 11th century.)