13" spout on a 16" auger

I'm looking at buying a new to me farm King auger. I want an 84' model so that trucks can pull straight up to the bin and dump. I currently have a 13x70 farm King and would like to increase capacity as well so I am looking at a used 16x84 farm King. I have quite a few old yellow top bins with remote opener hardware that is inside the collar. I am sure that the 16" spout will not fit in the hole so I am wondering if anyone has installed a 13" spout on a 16" auger with any success?