Create 301 redirects on 100k+ pages from two old sites to one new (different structure and databases).

We are transitioning our online store from our previous custom CMS to Magento. The old store exists at two separate domains and we need them redirected to their respective pages on the new Magento-based store. The two platforms are not similar, are using differently structured DBs and different server configurations. We are migrating from Apache to nginx. The goal is to establish a link between the pages (100k+ product pages) and create redirect patterns upon various similarities (reference parameters, SKU and/or other attributes). The ideal result will be to achieve seamless transitioning to the new platform for our customers and to make sure that all pages link to their new respective versions. This job is to : - Map the old pages on the two old domains to the new corresponding pages on the new domain You will get access to the databases of all three sites, in order for you to see a pattern for mapping the pages. I am attaching three excel files which represent a snaphshot of the structure on the new sites. The excel files have been generated with a third party tools and are just for you to get an idea of the structure and pages of the three sites.