Cannon's good but as Elvo hinted - it's STEEP from the top of the hill down to Nohl Ranch Road. If you want to skip that hill, you can take villa park west to santiago north, which turns into Santa Ana and you can pick your poison for where you want to cross over the 91 to get to SART. Taking Tustin will get you to SART without having to cross over the 91, which can be a little hairy.