Hello Client,
I have read your requirement about - Upgrade from PHP5 to PHP7 only, or Rebuilding from scratch in Symfony 4, of our web application. and I am sure I can complete it as per the given description.
I do have skills like HTML, MySQL, PHP, Software Architecture, Symfony PHP which you are looking in your project.
I have checked the link you have shared.
I Would like to discuss few things over the chat. So please do ping me.