Maybe there's something different with the SL than the SEL that I'm unaware of, but on my '88 560SEL I didn't go through any of that. All I had to do was line up the crankshaft to 0-degrees, and line up the camshaft notches with the respective line on the forward cam tower.

Now, in my case I had done a valve job and had the hydrolic lifters removed as well as the rocker arms. These weren't placed back on until the cams were back on and timed with a new timing chain (just for preventative measures)

Good Luck!