I have gone thru a few problems like this with engine builders, some BIG names.
At we had a 565 with break in time and 3 runs grenade and throw a rod destroy one cylinder, junk went into the cam valley, snaped the camshaft pin drive and bolt and you get the rest.
At first the builder was in disbeleaf, then he wanted the whole deal sent back, he deduced a rod bolt had broke.
he wanted me to buy a new crank, two rods, they wanted to fix the block etc etc.
I told him it was his responsibility to provide a new block and all the broken parts to be replaced.
it took 3 months and some threats of lawsuits to make it right, but they finally did.
I had to pay the freight both ways though, the engine was $17,000 new
Al