But aren't you supposed to multiply the ball python's length with 1 for the length of the tub, with 0,75 for the height and with 0,5 for width. And that is the minimum size for the bp's tank.
If you take a ball python of the usual size (about 48 inches), then a tank the size of 35 inches is too small. Decorations can also help if the tank really is too big. So I believe he's just fine in the bigger enclosure.