Hi,
I dropped my nearly 70 lbs in the last year using the old fashioned low-fat diet

However, if I were in your shoes and a follower of the Atkins diet, what I would do is actually what you mentioned. Shift the fats you eat from the traditional meat (saturated) fats to those found more in oils or nuts, for example. The way I brought my LDL-C way down was to aim for the lowest intake of saturated fat that I could reasonably attain. Most of the fats that I take in now are either monounsaturated or polyunsaturated (nuts, oils, soy). I do take in a little saturated fat, but I absolutely avoid trans fats/partially hydrogenated ... like the plague.
Maybe that shift in fats will work in your case? Just be aware that you might notice a small drop in your HDL-C also, depending on the amount of polyunsaturated fats that you taken in. However, your level of HDL-C is excellent right now.