MRT- I hate to say it --but the "noise tests on the ground" - that I know of -are as worthless as teats on a boar .
They are completely unrelated to the in air sound levels - which are the real issues.
You are chasing your tail -if you hope to have any power on any large engine using these antiquated ,stupid, worthless tests.
Sorry but you are the victim in this case of "sound experts" who are counter productive to fixing the real problem.
Basically - you probably will fail each and every test - till you put a 32 x12 prop on it .
The worst of it is -- you can easily keep in air levels way down ,using a decent power prop and any decent can type muffler .--and never letting the engine unload

Probably - your field officials will insist on the ground test -so-unless you can get them to agre to a subjective in air evaluation- you are doomed.