Your 17x3 will probably be ideal for your first few meetings, everyone needs a little time to get used to driving after a break
You could be competitive with a brushed setup and cells, BUT its much harder work than today's Lipo and brushless.
Personally if buying a new motor and cells for 2wd, i'd look at an 8.5 from a reputable manufacturer, and two packs of reasonable Lipo's (two should do for a meeting, but if your feeling rich you could get more to give you less stress about recharging)