If the inbound flight is in the late afternoon or early evening, you may want to try for an earlier connection. One hour and ten minutes is do-able under normal circumstances--an F gate implies he's coming in on an RJ, which shouldn't take much time to deplane, and then the walk/bus trip across to A-West should take about 15 minutes. However, PHL has issues with excess traffic that can delay landings and gate access at peak times of day. If the inbound flight is delayed and the plane has trouble finding an open gate, it could get tricky.