Hi Chris,
I propose to use 'Drupal Search API' and 'Search API attachments' modules for the PDF / MS Word searchability requirement. Usage of 'Redirect' and 'Broken link' modules would be explored to eliminate 404 errors and provide appropriate redirects. Style changes, tweaks and code merges (to the new site) would be performed as appropriate, based on your further inputs. I will ensure that the delivered items are responsive by following a 'mobile first' design approach.
Finally, 2 + 2 is indeed 4 and I look forward to a mutually beneficial relationship.
Thanks & rgds.
Ravi