Best size ceramic for 66" x 24" x 24"

[Zincubus]

All my cages have a UTH for the hotspot. The rest of the cage stays in the range of 77-81 throughout the day by way of the oil heater.

I like to offer a hotspot and a cool end but many here only warm the air in the room and do not bother with a hotspot. A gradient while good is not absolutely necessary in every situation. As long as I have a good hotspot and the ambient temps are within range Im happy and so is my collection.

UTH is presumably under tank heater / heat mat ??
I've got two of those already ( on a stat ) but I keep reading that they're no use for heavy bodied snakes so that's why I'm looking at going down this ceramic route .