unless you're buying the engine to get accessories, heads, covers or whatever, if you're really just looking for the shortblock I would suggest you buy a 1st quality new bare block rather than a second grade that many retailers sell. SDPARTS.com or CrateEngineDepot.com sell 1st quality blocks. You never know what is wrong with the 2nds. A good seasoned block is nice to start with. High miles should not be a deterrant on a used engine you're going to be sending out for rebuild, just be sure to get a gaurantee that the block will be rebuildable.