Another been there done that, only this time we ended up dropping the engine in my son's 964 turbo and removing the heads which then went to a machine shop locally to get the studs drilled out. If I'd known the shop was just going to drill and helicoil I would have done the work myself but £150 for 8 broken studs (yes I am ashamed to say 8 despite heating, cooling and reheating) wasn't excessive IMHO. With the engine out we did a mini top end rebuild and detailing job so it was worth the effort in the end.
On the subject of easyouts my advice is be very, very careful, if in doubt don't use them 'cause if they break you are into a whole new ball park. (That comes from personal experience and 35 years as a marine engineer.)
Good luck.
Grant
