I would use a 6PPC F/L bushing die purchased here: http://harrellsprec.com/index.php?crn=207&rn=384&action=show_detail because I know I would be receiving a die designed to size my brass the correct amount for the chamber being used. And, because I would also be dealing with two very knowledgeable southern gentlemen.
When dealing with production dies, the need for a small base die is a function of your chamber dimension, at the back of the chamber. I agree with the other poster that calling Harrell brothers is the way to go.