Shock absorber

I found these on ebay https://www.ebay.co.uk/itm/IKON-KONI-motorcycle-76-7610-Series-Bump-stop-rubber-25mm-15-34-38-000-0/132816399997?hash=item1eec796e7d:g:I-cAAOSw05Jbgoj1

and these https://www.ebay.co.uk/p/KYB-Rear-Shock-Rubber-Bump-Stop-Replacement-16mm-120341600501/1823291532

Not sure how suitable they are though.

those look OK. In terms of fitting them, just slice along the length with a Stanley knife then glue the cut together with superglue when in situ. When I first came across superglue it was used to make up O rings so should be plenty strong enough. Those rubbers are only bump stops so if the springs are correct you should never hit them.