JFK to AMS to FCO
You'll most likely arrive at the E or F pier, and leva from D or C. These are all connected to the same terminal building, in which you will also pass Schengen Immigration and security. Assuming your bags are checked all the way to Rome, you don't leave airside and could be at the Rome gate in I'd say some 30-60 minutes, leaving enough time for your desired Heinekens. Cheers.