A 13 year old kid I know ran a 13.2 100m (hand timed, no blocks or spikes) and a 7:06 mile (solo time trial, no spikes) last month. He's been training for about a year and a half. It's pretty light and consists of two speed days (3x100 or similar workout one day, 2x400 or similar workout another day) and one mid-distance day (2 mile run or 1 mile time trial).
He likes sprinting a bit more than distance running, but he wants to do the event that he'll be better at. Would this be the 100/200/400 or the 800/1600? His sprint times seem better, but his training so far has been more sprint-oriented, and he has the body of a distance runner.