I always bought my Helicoils and the tool to put them in with and the bigger tap from the auto stores but they don't always carry metric
helicoils so you may have to look around to find one ... in my experience Helicoils work as good as the original hole did so be sure you don't over tighten it ! it will pull out just as easy ! ....
however on aluminum engines the threads are subject to horrendous loads with all the flexing the aluminum does all a helicoil is is a thread the inside the diameter of the bolt your putting in it... the outside the thread is bigger and so you must tap the hole to fit that helicoil then put a bunch of locktight on the thread/helicoil and screw it in.... on the many I did they had a tang so your fork inserting tool could turn the helicoil...
that tang will bottom out your screw so it needs to be either down deeper than the screw sense it's near impossible to trim off the tang
once it's in the hole.... it is something to consider.
usually helicoils are short and I hate that ...they should be twice as long as they are commonly made but their not...
also put anti seize on your bolt before putting it into a Helicoil because excess loctite will squeeze out between the threads and lock the bolt some times .... if that happens you can't get the bolt out next time.... so antiseize will help prevent that from happening.
loctite is strange stuff it only hardens in the absence of oxygen... so a drip of loctite will wait there patiently for the bolt to be inserted then lock it permanently !
clean rags over the connecting rods ,pistons and depression into the crank area is a must when doing this ...treat it like a hospital room as you don't want drill shavings or tap shavings in the bottom end !
there are many ways to repair a broken stud or stripped out hole but the easiest is just re tap it for a slightly bigger bolt.... Usually that means also drilling out the bolt hole as well for the larger bolt and some places that is a big problem ....
that's why Helicoils were invented... you can use the same bolt in the same hole... you just have to put the new threads in is all.
all in all it's not that hard to do ...follow the instructions ! they usually come as a plastic kit with the helicoil tap and inserting tool as well as the loctite or thread locker.... at least that's how I bought them 35 years ago ! LOL
good luck ! please let us know how you get along on this thing !
....
Bob........