As we all know, Baltia intends on purchasing 747-4

As we all know, Baltia intends on purchasing 747-400's from an already established commercial airline. I am guessing that Baltia would select aircraft that a not due D-check or other extensive maintenance, so other than repaint and possible reconfigureing, what would be involved in putting these aircraft in service? Any additional FAA approval involved? If not I would say 6 weeks after purchase they cpuld be flying under Baltia's flag.