Where I get my machine work done, a line boring costs very little. Like 76 said, they cut the bottom of the cap slightly to make the *bore* smaller and then they run a true straight bore through them to make them round again. This ensures that the bearings will seat correctly and that the caps are not out of round and is a pretty good way to make sure that you get the same amount of clearance between all caps on a good crank. So it doesn't change bearing or main od size requirements which is good. The hone is just minor stuff though. Also, very much like Streets said, a *seasoned* block is often better than a new block since the core has already shifted and been put through its break in where it changes quite a bit during the heat cycling. I would recommend boring to straighten up the cylinders on all projects, and a minor true decking is often good too, this ensures that each cylinder is the same length and that you get a good seal on cylinder head gasket. This makes sure that the deck is exactly the same height from the crank centerline on both sides...something that stock cores often don't have. Just don't deck it too much since this *pulls* the heads in closer together and your manifold will not fit the way it would have before (also misaligning the intake ports, which can be cured by milling some material off of the manifold) since the heads are closer together and the endgap on the block to the manifold will be larger. Oh, and not to mention it brings up the compression. IMHO I would recommend that a core be tanked or baked, magged, given a boring, torque plate honing, slight cylinder decking if it needs it, and a line bore or hone, depending on which it needs. If the stock crank is being used then turn it and get undersized bearings. I feel that an engine with the right machine work done to it will be more dependable, less hassle down the road, less likely to give you surprises during assembly or later and will give you more power in some cases. If you are on a budget though, invest in a good cleaning, boring and hone, and just get the rest of the stuff checked if you are unsure. It's just money right???