This will catalogue various changes required for going beyond Classic. Another post may be needed for Kingdom of Sky (KoS), as that expansion would have class changes.
LordPazuzu Notes
For the duration of the Classic era, I've extended the high end of the level range for T5 global drops from level 49 to 55 to accommodate mobs above level 50 in Solusek's Eye and other high-end encounters.
T6 will begin at level 56. Someone can adjust that if/when Desert of Flames (DoF) is rolled out.