I haven't come across this construction "go so far" for arrivare.
yes, apparently "arrivare a" + infinitive can sometimes mean "go so/as far as + infinitive"
check this http://www.duolingo.com/#/comment/396584
Thanks for the clarification and the link. My guess is this construction -- it's just a guess -- is more common in spoken than in written Italian, but still it's a help to be aware of it. Thanks again.