I'm going to be useless when it comes to your specific question, but... GI doesn't really matter all that much if you don't need insulin. A carb is a carb is a carb, and whether it gives you a quick spike or a slightly lower one that lasts a longer while, your body'll have to deal with it, which is generally not good. For a T1 or an insulin dependent T2 (or one of the many other types), they'd need to know whether to split the dose, and then GI would matter. If you just cut carbs, without overcomplicating things with GI in the mix, you'd be likely to get excellent blood sugar control.
Just my 2 cents though.