#6-40 will give you 5 threads in a eighth. I guess that would require shoulder screws.
2 pieces tapped causes a jamb nut effect in the threads when tightening.
so you think that tapping the 1/8 will be enough? If so, i have the original small bolts that held the HEI module onto the GM distributor, do you know what tap to get to use these original bolts?