The return line is where it would need to be, return pressure is enough to return the fluid to the reservoir, but maintaining pressure is not an issue. You can use hardline which is cheaper (same as brakelines, just larger diameter) and attach to the frame. Steel lines will also help dissipate heat better than the rubber lines will. Another option for you is to use a tranny cooler from a GEN 3 explorer, as they are the same width as the radiator, and about 6-8 inches high, about 1 inch thick. This would be more than enough for a PS cooler....
SVT