When I said Shimano 8 might work for trainer duty, I meant that you might get the cogs in the middle of the cassette to shift alright. If you can't make 0.2mm shims for the spacers, 7 is the correct spacing and you should be able to lose the extra thick 7 to 10 spacer and add in another cog from another 7 cassette if you use ones with individual cogs. Some models are such that the largest cogs do not have splines and are useless if the rivets are removed. BSA BB shims should also work if you can find ones that thin.
Last edited by Kuromori; 10-23-19 at 12:20 PM.