Based on advice given at W107 Starter Removal, http://www.benzworld.org/forums/r-c107-sl-slc-class/1371180-starter-troubles.html and http://sl107.com/eve/forums/a/tpc/f/2346035941/m/7721085394, I used a 3/8-inch ratchet drive to remove and reinstall my starter.

Since there seems to be no published torque values for these bolts, I tightened them "by feel", approaching the amount of effort it took when getting them off...but no more.

Sorry that I cannot be more specific. Congrats on getting yours off...that's a significant Victory in itself.