Blanca, don't put high grade hard bolts in your swingarm spools my friend. You want soft bolts like the ones that came with the spools. The spool bolts are soft so they are likely to bend during a crash. If you go to a high grade bolt you are likely to break the spool ear off the swingarm during a getoff. We have one race bike with a missing spool ear and my friend GregBob is missing a spool ear as well due to crashing. I have a bent one on my gixxer from a getoff.
Another little tip,,,,,,,,,,,,,,,,, use the smallest swingarm spool you can find. I use Vortex spools. The smaller the spool the less likely the ear will break during a crash. You can weld a new spool ear onto the swingarm but you must remove the swingarm to do a proper job.
this is why i dont buy into the "swingarm sliders".
i wouldnt worry about it blanca, look at all the other bolts going through stress and cyclic loading far greater than your spools.