I just removed the camshaft from my '84 380SE yesterday and although I don't have any advice for you, I can tell you that the short intake side bearing tower bolts felt "funny" when I unscrewed them. I used an 8mm X 3/8" hex tip socket with an 18" long wrench. When I put the wrench to them, I would pull hard and they would just break loose with a pop. No gradual give. I thought I had sheared the first on off inside the block but they all came out fine but the threads were dry. The longer exhaust side bolts felt normal with the gradual give as they were unscrewed. I think in your case the impact wrench is the way to go although if the bolts are torqued to high to start with, there is that chance of galled threads.

Now I just have to figure out how to get the rear bearing tower out as there doesn't seem to be enough room to slide out the long bolt, it hits the firewall before I can remove it.