I've heard before that these engines were built with such high quality control in the factory in Japan, that a rebuild done on these engines by one of us will not yield the same reliable outcome of the factory built engines.
This information I've heard about this might be total hogwash too. I have no experience in rebuilding one of these engines.
Cutlass,
I tend to think along the same lines. I'm not positive I could get remotely close to the accuracy they achieve in the factory on a completely clean and flawless engine. Even following to FSM to a T. There's a video log of a 5VZ-FE headgasket job on youtube under the profile "worsethanchiggers" which looks extremely thorough and would probably be a invaluable resource.
Having said that, I feel I would be taking an even bigger chance rebuilding the heads and still not knowing the health of the bottom end only to save a couple hundred dollars; initially anyhow.