Sorry I was not more help to you buddy.

I'm really weird about my 400K external, or else i would let you borrow it.

Here is all I did to make a 400k bootable floppy used in my 512ke with my 400k external.

I went to this website earlymacintosh dot org. got the 3 images (System 2.0 Finder 4.1, released April 1985)

400k Write

400k Paint

400k System

I acquired these images with my powermac 7500

clicked on the image and disk copy opened up, showed it was a 400k image.

poped the 800k disk(s) in and it made the created and verified them.

then booted them up my 512ke /w the 400k external.