You may not need them at all. I have a Cr125 that uses those caps and I was under the impression that they were used to keep dirt, mud, and water from getting into the heads of the pins. Maybe the caps are stainless or coated and maybe the pins are not.. The pins themselves are allen and the pins get torqued, right? If it's a sportbike, most of the problems seem to disappear.
It also seems to me that a bolt would work as long as it doesn't get in the way.
I hope the impact works, it should, but if it doesn't drill bits and extractors are the next step. And that isn't fun.