I believe its very clearly understood that the RED ONE - both Mysterium and Mysterium-X - support 4.5K recording.
EPIC, as it uses the very same Mysterium-X sensor, has identical lens coverage requirements up through 4.5K as a RED ONE.
Of course EPIC goes to much higher frames rates than RED ONE at any chosen frame rate, and offers a lot of other systems level functional increases. So 5K RAW image width capability is just one aspect of the decision.
If you want to understand if your lens diameter provides enough coverage for a specific resolution its a pretty simple calculation
H mm ( 5.4 x Pixels H / 1000)
V mm ( 5.4 x Pixels V / 1000)
D mm = Sq Rt (H sq + V sq)