Unfriendly Inner Fender Bolt Holes

Ok...I've looked around quite a bit and saw where others have used the two holes on the inner fender drivers side as a mounting location. What I can't find is what size/pitch to use. I've tried M8 with a 1.00 and 1.25 pitch but neither wants to thread in easily. I'm scared of stripping the holes because I'm not sure there's enough metal to tap it to another size. So....those of you that used the holes....what size bolt did you use???

 

It's M8x1.25. The holes just got rusty. Ran a tap in there and bolts threaded in fine.

 

Almost everything on these are 1.25. I've run into maybe a handfull of 1.5 fasteners, can't recall anything 1.0. Just fyi -- glad you get it solved.