This has already been done, I cant find the thread about it.
Originally I helicoiled the super clutch to an M5 thread and used M6 shoulder bolts with M5 threads. This time I used M8 should bolts with M6 threads. The problem with M8 bolts is that their head and shoulder are too large. I wanted to use them so I could keep a larger bolt and decrease the risk of snapping. I had to turn down the bolt heads and shoulders in a lathe. My buddy helped me make a set up to make it easier to do. Worked really well.
Here is the original Super Clutch post with M5 shoulder bolts.
From right to left:
M8 should bolt, Turned M8 shoulder bolt, M6 shoulder bolt, Original bolt, Sping.