Your shop can also specify a swing weight and Titleist will do their best to match it. Usually the concierges can let you know if they can get to D2/D3 or your preferred swing weight.

I've done what you say many times. Most likely you will need the 14 gram weight. However, I strongly recommend you double check the swingweight with a swingweight scale. My exerience with Titleist clubs is that manufacturing tolerances sometimes lead to heads being a couple of grams lighter or a couple of grams heavier and shafts can be 1/4" longer or shorter, and this can produce swingweight differences versus the "theoretical" number of one or two swingweight points.

I purchased a light duty swingweight scale a few years ago, it is very accurate and it's the best investment I've made.