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I would try to make the 301s fit where they fit best.  Surely he still has some of the same type of pages - contact page, some informational pages, etc?  When I redid my SEO page, I had a lot of "loose" pages lying around. I put them on what I thought they fit best - so instead of having 3 or 4 sales pages, now I have 1.  I redirected all 3 to the 1. Where would your biggest issues be? He will have had old canonical links and new ... is so much changed that the site isn't really related to the old?  If you want more info, you may have to give a bit more on exact issues. ~M

As always a very good response. Congratulations Moosa.