Technically you should get the mains lined bored when you switch to ARPs. I would assume you need to get the big end of the rod checked as well. IMO, the stock main bolts are fine for 500 whp and will save you a headache and money. I hope so cause that's what I have
IDK what the rod bolts cost, but if you need to get the rods machined because of the bolts, then you might be better off spending $350 on a set of forged rods.
Maybe Bogus will chime in on the machine work part...