The 85 sounds good for your son, just make sure he gets a good deal of saddle time and learns to control the bike *before* he hits a race the track.
As for you, I would suggest a used Honda CRF 250 R. They are pretty doggone solid bikes, and pack a lot of power.
If you are adventurous, try a CRF 450 R. My "cabana boy" (er boyfriend that is) is roughly the same size as you, and decided that a 450 R was a blast, but a little too much bike for him since he was only playing in the gravel pits about three times a year, and he hadn't ridden in quite a few years...