1. I'd take the site glass out. You'll kick yourself if it goes pear shape and your back to square one.
2. Because its raised lettering, do what the shop say's. I used a smooth file to get the lettering flat 'before' I had mine PC'ed, then its easy to remove the PCing after its done. Tape off around the lettering to protect from accidental knocks.
3. mask up ALL area's inside the cover and plug threads.
oh yeah, and as Speeddog say's worry about the seal as well. I just bought a new one and fitted it after job was done.
How the heck did you get the oil seal ring out of the clutch cover side? I got a new one so I see the shape but mine wont budge. The rubber on it's already all torn up from me trying and I keep trying to wedge a screw driver between it and the copper bushing below it but no luck. Maybe need to pick up a very small and thin chisel? I also tried a little heat (butane torch) to no avail.