Taiwan beauty caging advice

OK when I got my Tai I knew he would get BIG (8-9 foot) I saw a recent pic of the snakes parents owner (Bill from great vally serpentaruim) The snake is massive! The guy has his hands above his heaad and the snake still touches the floor. Mine is already about 38-39in long and only a little over a year old. What do you think I should house it in as an adult. I mean my grandpa and I can build what ever we need( he has built cages for my grandma when she did wildlife rehab). Any way I want to get a nice size that would compensate a 9 foot snake that is about as big around as a bull snake. Thanks in advance guys!!!!!

I would go with 1 sq foot per linear foot of snake with room to climb and plenty of space to hide.