What could I run for 400m/800m?

Yeah I think you can PB in both events right now.

I can see the 800 being sub 2:10

What about the 400m?

400m: 54-55

800m: sub 2:10 at least. Hard to say more since a lot of other factors go into racing and training for an 800m. Work on endurance a little more (while keeping 800m pace and faster stuff) and you'll see your 800 drop a lot. Work both ends of the spectrum. Faster than 800 pace and and slower than 800m pace, mile all the way up to marathon pace and everything between.

'Do you think I could potentially run a pb in either event?'

Yes your 300m is fast so 400m pb should come soon

Your 800m is weaker but as you are only 14 that will come down a lot, but over more time. Still in pb shape now and as others said sub 2:10 is on the cards.

Last year (end of October) I ran 1000-800-600-400-200 with rests of 4.30 4 3.30 3 in 3.16 2.33 1.52 69 30... went on running 53-2.03 (bad period) in January and 51/1.57 summer season. I am not a distance guy, though. I could run 22 high in training in top shape.

I doubt this is for real, but if you are really 14, you could potentially run very fast at some point. I ran very similar times at 14, but could run 48/1:58 by my senior year. Keep training and you will easily run faster each year as you grow.

My 200m pb is only 25.78 (set into a -3 headwind), so that my be a hindrance.