In the absence of a chain guide, one can use copious amounts of zip ties to keep the chain in contact with the cam. When I did the chain on the 560, I didn't like the way my 10mm fit in the cam tower bolts and didn't want to strip one. Instead of the guide I used samll zip ties to keep the infeed of new chain and the outfeed of old chain in contact with the cam. Probably adds about 15 minutes to the job.
I did attempt to just keep the infeed in contact by hand, but the outfeed is just as important. Very easy to jump time if the chain isn't in contact with the cam from both sides.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.