I would add that you want to figure out what class you'll be racing in. 10.5 and 8.5 are too fast for stock (17.5) and too slow for mod (well, depending, but 6.5 seems common around here). So, go to your local track and figure out what you want to race.

As a side note, running novice with a 2WD 8.5 buggy is... pretty nuts.