The easiest way to ID a 360 pan it has a unique end for the rear main seal gasket which is smaller than the others.
Here's the end with the unique gasket for the 360 which has the rib around the gasket seal radius. If you see this rib, then it is a dead give away that it is for a 360 only:
If you need more detailed information on identifying a SB Mopar oil pan, refer to my thread that I just made on how to ID a SB Mopar oil pan from 60's to the 80's:
