Mercedes 617 Harmonic Balancer problem
 

My vote is to go for the drilling two new holes option.

I read somewhere (it might have been here it might even have been on BW) that you are better off getting 3 flute drill bits as they drill a round hole whereas the standard 2 flute HSS drill bits tend to drill a slightly oval hole. As we have seen oval holes are not what we want.

If you disregard the difficulty in drilling two good straight parallel holes the biggest problem that you'll have is stopping the crank from turning when you come to apply the monster torque to the 27mm hex head bolt.

I'm collecting good ideas for this problem here - the special tool post #9 is the one to get but it ain't cheap.

http://www.peachparts.com/shopforum/diesel-discussion/284511-has-anyone-ever-made-good-diy-tool-lock-om617-flywheel.html

Make sure you get the spring washers under the 27mm hex head bolt the right way round.