Only depth difference in the bell housing that I have seen is a C5 design that is deeper as mentioned.
I measured 6 bells today, all bolt to the pump bolts. All were the same depth at near 6 inches.
There were 5 bolt bell and 6 bolt bells. All were the same depth. Some were small converter bell, some were the large converter bell. I have never seen a difference from case fill to pan fill bell housing that bolts to the pump.
If you do not have the correct converter and flex plate for the belll you are using , there will be fitment problems