Ok, I can't believe I missed this, so I might have found the answer myself....
2 identical sleeves 20mm ID, 25mm OD for 85mm with 3mm thick x 31mm OD flange at one end (88mm total sleeve length)
These are inserted into each side of the engine, but the flange on the right now means there is not enough space to fit the swing-arm, so replace the steel spacer beside the right hand swing-arm bearing, (originally 23mm long) with a 20mm version (aluminium should be fine, it only runs in a seal, not the bearing), which ensures the overall length is now as original.
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Can anyone confirm this information, considering what I found, it makes a whole ton of sense. I can't really imagine having the swingarm spread apart 2.4mm-3mm to do this install. So me thinks I found the answer.
If this is right, I'm wondering if you want to quickly add this small detail to your Swingarm Swap Document (Appendix C) Ben.
Someone add some insightful stuff here, cause I'm a little confused