One side done!
I got the M6x1 kit from Autozone. It came with 12 inserts and I used 2 per hole. Piss poor instructions but simple installation. I wasn't sure if the tang needed to be broken off if it bottomed out in the hole. I broke them off anyway. The second (stacked) insert was a little scetchy as I didn't know how tight to make it and it didn't seem to "bottom" on the previous insert. That said the left side is done and the cover bolts went in with confidence. For anyone considering this fix, go for it. Piece of cake with the supplied tool and tap. All you need to add is a 1/4" drill bit and a tap handle. 30 minutes for all four holes on the left side.
Thanks all for your input.