Miss-threaded the top hole for a top starter bolt

[Markopolo]

I changed the starter on my SW2 98 and somehow I miss-threaded the top hole for the top bolt. I was able to tighten the bolt only about 1/3 of its way. I feel the thread will be stripped off if I screw it fully. The bottom bolt and the partially screwed top bolts are holding the starter for now.
I am not sure what would be the best way to fix the internal thread in such a narrow place. Do I need to fix the thread by using the tap 8mm x1.25 or will it strip the thread? Or do I need to replace my old thread with a thread insert? How hard would that be to do in such a tight place? Has anyone had the same kind of problem? Does any one have a better idea?
I was also thinking to put in some sort of studs instead of the bolt. I read somewhere on the forum that someone did it. What kind of studs did they use? Where would I get them?