1000 feet in a mile is 19% and quite steep for repeats and sprints. I would think that for a “hill run” 300 feet per mile would be the minimum to consider it a hill run. Less than that would be a flat run. 300′ over 7 miles is not a hill run that’s only 40 feet per mile.
Just FYI… my first “steep uphill hike” was 2500 feet in 8 miles (Mountaineering program after my 8-week Transition period) and it left me sore for three days. But all hill workouts after that have been fine. So I would expect it to be a big day for you. Maybe aim for 2000′ for your first one!