One concern is that this medication is not only a pain reliever it is also monoamine reuptake inhibitor and this dose could potentially result in Serotonin syndrome. Serotonin syndrome can cause tremors, seizures, increased breathing, a dangerous increase in heart rate and elevated body temp.
You could also see extreme sedation or hyperactivity with this drug.
At a high dose this drug can be given at a dose of 5mgs per pound once daily so this is far above the high end of the safe dose.
I know this is not what you want to hear but even though he may have vomited up the pill I would suggest having him seen at your vet. He may need no treatment other then some IV fluids to help flush his system but he should be closely monitored for the next few hours. I would feel safer having your vet keep an eye on him for the day. If seizures, elevated body temp or increased heart rate develops then they will be able to address it immediately.
I would like to tell you to just monitor him at home but I would hate to see serious complications develop and then see you rush to get treatment.
Hopefully he vomited up most of it, however being monitored for the day would be in his best interest.
Please keep me posted on how things are going. Please reply back if I can be of additional assistance.