I have my 8 foot male in a 72x30x18 cage. Also got my 6 and 7 foot boas in the same size cages.
If i had a female retic, i would go for a 96x30x18. If you go deeper with depth, be sure to add height so you dont have to literally slide into the cage to clean the back wall and corners.
Here is what my 3 T25s (72x30x18) cages looks like. This is a little older pic as i changed back to aspen and everyone except Vicky in the middle cage have broken their silk vines lol.
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