ya, your guy can go 156-7. 800m. if you peak him right and get in the right race.
really you want to get his speed down to 23x in the 200 and simultaneously develop strength.
this means going to the gym and doing a sprinters program.
and add in 1 to 3 minute hard hill repeats - two sessions per week, along with 30 minute cross country runs in the morning and hard sessions in the afternoon.
here are example schedules of the great 800 m runners.
http://tonywilson.wordpress.com/2010/05/05/base-training-for-the-800-m-runner/
but do not attempt any of these schedules. you need many years to get there. and these guys started with the 400m speed already fairly developed.
i looked around for a peter-coe schedule for sebastian at age 18 and modify it for your guy. but i can't find any so let me make one.
Fall september to december. buildup part 1.
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the aim of this training period is to build a base for sprint training while adding strength. if you recover properly there is no risk of burnout with such a schedule.
every morning 20 minutes cross country run of 3 or so miles,if you are coming off a hard day make sure you run relaxed and recover. then do 10 x 120m stride outs fast but they must be completely relaxed. and with full recovery between.
afternoons.
monday- 10 minute jog, stretch (lightly).
10 x 40 seconds hard up a steep hill. 2 minute recovery.
rest 15 minutes.
6x120m strideouts on the flats fast but as effortlessly as you can.
tuesday
hit the gym, abs, all round upper body. light stretching for 30 minutes after you finish.
wednesday
10 minute jog, stretch
6 x 2 minute hard up a steep hill, 4 minute recovery
rest 15 minutes.
6x120m strideouts
thursday
10 minute run, 10 stride outs, 10 minute run
friday
10 minute run.
four sets of 10x40m relaxed fast. walk recovery between until breathing returns to normal. between sets light stretching.
10 minute jog.
saturday gym, leg work, leg press, leg curl, leg extension, abs, and upper body. lift hard, reps 80% max to failure.
lift for 45 minutes, take 15 minutes off, hit it for 45 minutes hard.
sunday run 60 minutes cross country. if you are sore, take it easy.
---- jan feb and march----(schedule to be provided later) real sprint work and continue the build strength