... but.... what kind of overbanked curve are you talking about?? And fitting into what sort of layout in what way?
Just as a small example; you could be talking about an overbank that is very tall and that turns the train back through 180 degrees to send the riders back the way they came, like a hammer head. Or you could be talking about one that stays low to the ground, only turns through a few degrees and basically just flips the train nearly upside-down and then back again.