Well, it turns out that the gasket is bad AND some of bolts were loose. I tightened the bolts and the leak is not as bad. I can't hear it anymore, but I can still see some smoke escape if I overfuel my engine while watching the manifold. I guess having those bolts loose isn't too bad since I know I won't have a tough time removing the manifold.
However, I will be running quite short on free time for the next month or two. This leak has existed for quite a while now. Am I running a big risk of permanently scorching the head by not fixing it right away? I would really like to hold off on repairing this, if I can. If I am risking damage to my engine head then I will just cringe a little bit and ask American Express to have it fixed for me.
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K