The piston set yau have is probably of a OM621.910 190D (1958-61)30kW-40hp. The funny thing is that the catalog says it's also for :
OM621.912-.916
OM621.918-.919
OM621.930-.932 -verbatim
If the catalog`s correct (and it is)those include
W110 190Dc, w100 200D ,some types of Unimogs and light weight MB trucks. If you want to sell it,it`d be quite easy...
However, this cat. says 87,50mm under KS Nr
90 989 610
Once again ,good luck!

by the way, what`s the manufacturer?