what to put in new cage

[Them and Us]

on an impulse today i bought a cage that was on sale at a shop called Animabilia. it was 60 bucks. 3 feet high, 2 feet wide and 2 feet deep. i have right now two snakes. a gray rat snake. hes about 4 feet and a half to five feet and my BCI which is only about a foot and a half. the boa is in a 20 right now and rat is in a 30 long. I'm thinking give the rat the new cage and switch my boa over to the 30 long for a while until i build his permanent enclosure. will a rat utilize that much height? will a boa?if so he can have the cage and I'll build the rat a new one. im told its bad to keep boas together but is is likewise for all snakes? if not i would love to buy another rat to keep in the new larger cage as well. thanks in advance for any help and insight given .