My first rebuilt engine did 9kms and died. Well it didnt die it just lost oil pressure. So i threw it all out got a new motor and started over.
In my opinion.
Get a virgin block if you can. And use the 86.5mm pistons.
Make sure you have a new oil pump aboove all else.
While its apart get the new rings for sure.
If you have the money buy forged pistons in 86.5mm, h beam rods and Metal head gasket. Toughen it all up!!