Just coming back to note that I checked my Haynes manual and the timing mark/sensor bracket pictured there for the M104 is the same as in the picture that hirnbeiss posted. As you say, yours is different. The one in your picture is the same style as the one on my M103 (91 300E 2.6). The TDC mark on mine lines up with that tab at top dead center. The only difference on mine is that the tab lays over top of the marks on crank (the bracket is the same but my crank markings are either wider or the crank sits deeper).

In your pictures, it appears that the cam gear marks wouldn't line up right no matter where your crank was and that is kind of strange. As you said, you want to find TDC on the crank so you can understand better what's up with the cams. I think what gmercoleza was suggesting was that you put the oil dipstick down the spark plug hole, turn the crank and observe when it's at its highest point. It should be pretty close to TDC, then look and see where your timing marks are. It apppears by the presence of red rtv on the timing cover that it has been apart before. Anything could have been messed with. You may have to set it up again from scratch, but again, I really don't know. How you proceed from there is something I wouldn't want to make suggestions about at this point given my lack of familiarity with the M104 and variable valve timing.
Good luck, please post how it works out.

including a timing poiter from the junk yard or being a tooth off of one or both cams