Never had to Bill,
have done lots of o/size stuff on EJ's, they recommend .5mm on some models, I have gone to 1.0mm on turbo units as well without issues. Although they were closed deck. I would probably have a good look at where the reliefs are machined out for the inner case half bolts before I decided to bore out with out resleeving-I have had many that have split down this section when loaded excessively after boring out! Even on a std application EJ22! What did you have in mind?
Sixpack