How many Tylenol Pm would result in post mortem blood level of Aceteminophen 1200 mcg/mL;?

My husband recently ped away. A death certificate was issued as Respiratory arrest due to acute mixed drug intoxication. 4 months later the "authorities" want the death certificate changed to Suicide. How many pills would a person have to ingest to reach the level of 1200 mcg/mL Acetaminophen: 40,000 ng/mL Diphenhydramine? Would an allergic reaction cause these levels to increase? Husband had history of Asthma.