That ping may just be the pingtime to the site you're testing your speed on. You should ping HTC's server directly to get a more accurate number, but as other's said, under 300 will work, and 100 and under is optimal in my experience. I'm around 80ms now, but I've played before with 40ms, and there is a difference in how the guns affect targets just with that 40ms difference, you can see it, and it adds lethality a bit. Still at under 100, I've never had a problem being competitive with that. Bruv is one of if not the best player(s) in the game, and being in the UK his time will be much higher than 100 I believe.
So, don't be too concerned IMO, your connection should work fine. Our lake home has the same sort of rural wireless connex you're using, and I've flown on it before and it was completely playable.