I try to travel "light" (e.g., carry-on suiter and 21" upright trolley); this saves considerable time and I have been able to catch a connecting flight in 75 minutes. The main time consumers were passport control and getting through security (arriving on an international flight in PHL you will always have to pass through security to catch your connecting flight). If you really need to check your luggage I would try to get a 2 hour connection. But considering the two later flights you can just take the gamble.