From the pictures it looks like the cog has to go out. You need to take washers/spacers from the cog side of the hub and move them to the non-cog side. Then you have to redish the wheel, which will actually make it stronger because you are removing dish.
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Il faut de l'audace, encore de l'audace, toujours de l'audace
1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1