I've built 5 blocks with the stock bolts, never line bored them...they were fine. Mine's currently got 28k on it.
Did 2 studded blocks, and did the line bore, that's pretty much required.
Make sure that the pistons are in correctly, they do have a front and back side. Keep things clean, and give the rings time to seat, but other than that....drive it like you're gonna drive it.