Welcome to the world of Low carb, LFKA!
Your question is valid, but I'm afraid it is impossible to answer.
The reason is, there is no direct connection between GI and GL values - which I know doesn't help you figure this all out.
On Montignac phase 1 when it tells you to stay below 30 GI, you should stay under GL of about 10.
On phase 2 Montiganc when it tells you to stay under 50 GI, you should stay under about GL 20.
So the trick is, finding the foods with both low GI and GL. www.mendosa.com
has a good list of foods with GI and GL listings.
Now, just to complicate things a little further, personally I put more emphasis on the GL of food than GI. So I'm not really following Montiganc any more because of this.
Re your comment about eating a lot of low GI foods, just because they are low, and therefor ok for you... not really - The GI of a food won't change regards of how much you eat. This is because it is a value that a food is given relative to another food (commonly glucose) for the SAME AMOUNT of that food. So the GI value is based only on quality and not quantity. This is pretty much where Montignac finishes, and doesn't necessarily go far enough.
The Glycemic Load (GL) is a value that is based on both quality of the carbs you are eating (i.e. Glycemic index - or who your blood sugar level is raised for x grams of the food compared to x grams of glucose) AND the quantity of carbs in the serving.
So Glycemic Load = Gylcemic Index x the amount of carbs in the food.
I would recommend the "New Glucose Revolution : The Authoritative Guide to The Glycemic Index" by Jennie Brand Miller and others. This is what I follow now, and has quite simple to understand principles. This is the source of much of the information in the mendosa site I posted above.
Hope this helps!