Didn't read the whole thread so sorry if I missed something.
The external floppy drive used in Amiga external drives is not a bog standard PC floppy. The interface used can be converted to use PC drives but the drive is not a PC floppy drive.
The internal floppy and Gotek thingy connect to the Amiga in a different way to the external floppy. They are very different. You cannot remove an internal floppy drive and simply stick in an external case so the same would apply for the Gotek. I am assuming that the interface sold on Ebay has been designed to work as a special interface between the two. That I assume is a tested product.
The external drive mod cannot accommodate the Power Computing XL drive.
The A1011 does not have a pass thro and is truly a strange beast.
https://www.scuzzscink.com/amiga/scuzzblog_april20/scuzzblogdapril20_2001.htm
