Also has to be free of all common allergens (ie. gluten, casein, soy, eggs, etc.)..

Most I've seen including what I used to have don't have the 1:1 ratio and are either 2:1 or 1.5:1 calcium to magnesium... I would like to get a 1:1 or as close to it as possible per my nutritionist... thanks

Hey!
I use Natural Factors Calcium & Magnesium and it has a 125mg:125mg of the both. Mine has added potassium, zinc, and manganese, however I am not sure if you want that, or if they have one without it. I am not positive if it is soy-free, but it is dairy and gluten free. Hope this helps!

yep, 2:1 is about as close as you're going to get (and what I had heard was the optimum ratio, but in a special needs case...
I take rainbow light, as it has the right about of D as well (for bone formation, and since I'm in a high northern latitude these days), plus a couple other herbs, but is free of the common allergens (including gluten). it's 2:1. you may have to add additional supplementation to get to 1:1.