Reptile's got over 10k on his rebuild and Bluegtp has over 6k on his (and no one thrashes on a car like blue. LOL) and neither are even close to stock. I think if done right, emphasis on that part, they will last. I realize 10k and 6k aren't a lot in the grand scheme of things, but I wouldn't hesitate on rebuilding another one. But then again, I'm a stickler for exact specs on everything which I think is the key to a successful rebuild.
And as far as steam cleaning, never heard of it. Take the important parts, block, heads, etc. and have them boiled out at a machine shop. Just my opinion, steam is water, water and bare metal will equal rust if you don't get it together right away. If you do steam clean it and it's gonna sit a while, spray it all down with some WD-40 or something equivalent to keep any surface rust from forming.