Skip the T-8,,,, I think its way too small and will only be a short time cage. Reticulated pythons use arboreal spaces and are rather active when given behavioral options that include climbing and perching.
I can't remember his percentages of SD/D or if he's all mainland, but I'd prepare to cage him in something 6 feet wide, 30" deep and minimum of 2 feet high.
A T-8 is what a lot of people get for their royal pythons.
He's a great looking specimen and I love those last pictures.