To predict final gravity, it's really easy. Grab a crystal ball, and peer into it to access the wisdom of divination.
No seriously... predicting fg is impossible. There are too many variables at hand. However, I can say at least this from my personal experience. Given that your grain bill doesn't contain any dextrin rich malts, that you're mashing at 149 (a somewhat low temp) and that you're using California ale yeast (a yeast with good attenuation characteristics), you should get very good attenuation. I'd ballpark it around 80-85% if you get a good starter going. Given those numbers, you're looking at FG between 1.012 and 1.017. But at best, I'd call that an educated guess.