Well, ball pythons really don't need as much space as you think. I think a 74qt tub is just over kill. Its just twice as much space as you need and you have to heat and cool that space. For me it would just be a pain. The ball python will be perfectly fine in a 42qt, but a 74qt could pose some problems. Stress from being too large, not getting temps right, etc etc.
IRIS tubs. You can also buy them at the container store if you have one near you. They aren't really obvious that they are iris. They only have a tiny logo on them usually on the bottom of the tub I believe. When I bought them they weren't even labeled as having a brand.