The aluminum is much softer than the bolt.....so the aluminum is where the threads will strip.

If you look at the side of the cylinder, you can see the place in the casting where that bolt goes - you have little chance of doing a proper Helicoil repair in that area without taking the head off.  Also...most helicoil inserts are only the same length as the thread pitch - (6mm in this case), and the threaded part of the aluminum is more like 14mm.  So you will need a longer than standard Helicoiil insert.  The tools you get when you order the kit are not long enough to go through the length needed.

I think your best chance at a repair (without removing the head), is to buy a piece of 6mm threaded rod, insert it into the hole and thread it lightly into the hole and see where it bottoms out....then mark the rod, remove it and cut it to length.  The threads on the bottom should have a slight taper on the end, and there should be some small slots cut to help the rod cut some new threads into the aluminum as you bottom it out in the hole.  Then when you put it back in apply some permanent thread locker and screw the stud down into the cylinder tightly using the "double nut" method.  Let the threadlocker harden for a day or two....then put the nut on top and see if you can tighten a nut onto the stud.....not sure if you should try to torque it.....I would be apt to just make it pretty snug.

Here is a repair I did to the stripped hole just behind the one you have stripped.  The good news is the one you have stripped is not in the oil galley like the one I repaired.  This shows the longer insert needed for the Savage head.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1448209911

I made the 6mm stud for you.....if you want to try it send my your address and I will mail it (you pay me back postage).

Can you take photos and document the process....and let us know if it worked?

What's the nearest but bigger SAE bolt? Daves plan sounds great.

With a cut off and dremel you can slot the bolt and make it workk kinda like a tap..The slot isn't from edge aimed at center, much more shallow. Done it several times

Well o course not,that slot is first in..and, it wass For the other guy. But glad you mentioned it. Gives the idea more credibity.

What Dave has suggested is a great idea provided sufficient original thread remains. Also, will the head cap go back on with the new stud sticking up.

Whatever you do end up doing use two quality taps. One ground off to reach the very bottom of the hole. Cylinder heads are expensive, tools are cheap. If you can figure out a method, a Helicoil is probably the best way because  you will be able to use the standard bolt. Also, do you have compressed air to blow out the hole.

Good luck with it.

Dave,
That would be very nice of you.
A repair like this is tricky at best. Especially trying to do it without removing the cylinder head.

Yep.....those shop rags are "seconds" - but they were free!  A friend of mine got a few bags of them from a uniform/rag business that supplies those things to shops.....the bag he gave me is a 50 gallon trash bag and it is jammed packed with them.  The rags have some holes, tears or stains in them.....so I guess the company took them out of circulation.  I am set for life with shop rags!

After thinking about this for a few days....I am going to take a "bottoming tap"and weld an extension on it - so that we can get as much good thread in the head as possible.  This hole is not in the oil galley - so making some chips while cutting new threads won't be the problem that it would be if the stripped bolt was the 130mm one at the left rear side.