If it has MWSC billet rods don't bother replacing the rod bolts, replace the whole rod if it makes you feel better. There are only so many cycles on an aluminum rod before it should be replaced. Replacing just the rod bolts would be like patching up a hole in a dixie cup.
If you have MWSC rods they are pretty tough, I've run my engine over 13,400rpm last year more times then once. I'm replacing the rods this season before they break. If you are only running it 8-9000rpm my guess would be that you have another season in the rods no problem. Anytime the engine is apart, always install new rod bearings in these kohlers.