[t_shee]

Would it be ok to drill it out and tap it 1 size bigger

If u go to 1/4" bolt itd only be slightly bigger so that should work well for u if u end up having to go that route

 

[t_shee]

Maybe try a thread chaser.

I think hes referring to the bolt between the motor mount holes. The one thats missing

 

[t_shee]

I believe the thickness of the gasket is important in how everything lines up. I wouldnt be too happy about that personally. If they wanna yamabond it then they could put it on both sides of the gasket. I have had great success with 6mm helicoils but the cases will have to be split to do it.