Hello,
my name is Josef, i'm professional programmer from Czech Republic, and i would like to apply for this project.
I understand your requirements, and can make all your PHP5 files PHP7 compatible while preserving backward compatibility with PHP5. I'm very familiar with both PHP5, and PHP7 including changes between versions (since early PHP3), so i'm confident i can finish this project quickly and to your expectations.
If you considering me for this project, feel free to contact me by chat, where we can discuss all the details. I'm looking forward to hearing from you soon.
Kind regards,
Josef