I just looked at an old (2005) Poston catalog. They don't mention anything about a pick up, but didn't they come with one? That pan has an 8 quart capacity, so it would have to be different than a stock one. Maybe Steve Reynolds could make you one?
I spoke to Jim and he told me to weld a cone to the bottom of a stock pick up tube. I was hoping to try the TA deep pan pick up but I was told it was discontinued.