Stock racks...what do you use?

[Mayhem]

Dave - you could notch the shelf support / divider so it maintains the same line as the diagonal (below left)but given that this is not a critical component, I wouldn't worry.

Given that you (like me) are going to be welding a front angle for each shelf, the simplest thing to do would be to weld this in first and then simply square the shelf support off of the rear upright (below right).  The front rail is welded to the diagonal so the small gap between the shelf support and the diagonal isn't an issue.