Not sure what to make of this. Seems like a lot of intensity before a race you're looking for a prediction for. 3:30 is also a lot of rest. I would guess those reps were 3k pace versus 5k pace. Maybe somewhere in between. It reads like you hammered that workout.
Definitely under-16. I think 15:45-50 or so is about right. Again, pretty hard to tell without knowing other workouts, the goal of that session, & how you felt. Maybe that was 5k pace or the 800 was 5k pace and 15:30ish is your mark. I wouldn't open faster than 5-flat & would think 5:05-10 would set you up for a strong race. This workout will still be in your legs.