even the block is new for 6 grand
Remember one thing. All the pros prefer used blocks. Of course, they call them "seasoned", but that is what they like.
A new cast iron block, has stresses in it from the casting and initial machining. After a few thousand heating and cooling cycles, plus the forces on it from running, it has lost most of that stress, and has changed dimensionally in tiny ways.
Re-machining it will add small amounts of stress, but not much. Not nearly as much as it had new.
Of course, you run the rise of getting a bad block with a crack somewhere, but that is what the warranty is for.
Plus, a certain percentage of all the blocks come out of the casting process with flaws.
Most of those are found during the first inspections, but a few get by, so new does not mean perfect.
Remember, the key here is, you are buying a rebuilt engine, not a used one. Used is what you buy out of the junkyard.
Rebuilt quality is more dependent on the skill and care taken by the rebuilder, than the parts he used.
As long as he uses name brand, quality parts.
