Builder says customer supplied the (possible used) lifters and the (overlength) valves.
Customer says the lifters broke and would not slide out of the engine. Also says the springs were too tall. Builder says the customer supplied parts dictated the springs available at the time.
Customer says he did not like the assembly. The only fact provided here was the balancer, which I also don't like.
Customer runs engine at high (8000) RPM. Admits that the valve lash was not checked as frequently as it should have been.
I completely understand not wanting to send the engine back to the builder if faith is lost. Maybe the builder has a policy that they must be the only one to perform the post-mortem. That is not mentioned here.
However, if you can't even discuss issues with the builder, it's MHO that it should not be discussed in a public forum either. The builder has no idea there is a problem and is unable to address it.