What sort of times were your 400's?
Your km rep isn't far off mine, and i'd be on the fringes of a sub 5min mile.
I've done a 4:45 1500mtr track race which is about 5:05 pace for a mile, and i'd be doing "hard" km reps in around 3:18-3:20.
So on some fag-packet calcs you might be currently...