I *just* finished my conversion of the same refrigerator. I had to cut a hole in the back to accommodate my co2 tank and noticed that the coolant lines were against the plastic. So I thought that was the way the whole fridge would be. I was wrong. I cut the top, thinking it would be safe going top down, luckily I was still careful and was just trying to take the steel off the top. As soon as it gave way I grabbed my vice grips and peeled it off. There was a coolant line right down the middle and was about 2mm away from slicing it. So if you're trying to convert this fridge, be EXTREMELY careful.
On the plus side, my dual tower is nice a cold without any mods.