Is 100 minutes enough to transfer from PEK Term.#3 to domestic Term#2?

I arrive from USA in PEK at 2:40PM. My connecting flight to Kunming (Term. #2) has been changed to 4:20 PM. Chinese Eastern tells me I must check in one hour before departure (3:20 PM). Is it realistic to get through immigration, etc and to Term #2 in time?