Cubecart 4.3.8 store converting to latest cubecart version

My client has a cubecart store which is in drastic need of a re-build to bring it in-line with todays coding & technology.

They wish to keep the design look and feel but have it re-built on the latest version of cubecart as they are invested in the platform and it's systems.

Requirements for this would be full migration of site - create custom skin for new cubecart version (based on current version)

Full details of the site will only be given on application as I have had PPH users go directly to my clients before which I do not wan't happening again and is against PPH rules.