You could use a stock, 5 qt. pan and pick up for same. It will clear a 3.75" stroke, just check it to be sure that it hasn't been bent previously- the OEM pans will clear a 400 stroke crank, though.
If you need the extra capacity and depth, there are other pans that have the same "footprint" as the OEM pan, only deeper. It would obviously require a deeper p-u.