Sorry to hear this! Been there myself 3 times in the past few years with 3 different, well known builders. I wasn't trying to be cheap but I didn't want to pay the money Sterling charges. I have had 3 different shops here in south Florida, do jobs for me, have multiple problems, pay to rectify those problems just to have more problems. Each time when enough was enough, you end up finding all the shortcuts that were taken. (only 4 new pistons, mis matcher rockers, used parts etc)
Now I send everthing back to Sterling. It is a little bit of sticker shock when i get the estimates but the engines come back perfect and there are no issues. In the long run you end up paying less. You only pay once for the repairs and once to RxR the motors, let alone the downtime and aggrevation you save. You finish your runs! From now on I will only use Sterling, Period!
I love when the other builders say....get the motors over to me. No regard for the time or labor to pull them and transport. They can care less about your downtime and best of all, If there are other money making jobs in the shop, you wait!