Refactoring of old PHP code and adaptation to PHP 8

Good afternoon.

Need help, need to do refactoring for an old project.
The project consists of 35 PHP files with a total size of 400kb - a procedural style, instead of array objects.
The project is now running on PHP 7.4, it is necessary to adapt to PHP 8.0.
It is advisable to fix all notices. For 7.4, it is mandatory that 8.0 does not have Warnings.
In refactoring, it is also necessary to register the processing of incoming variables from POST/GET in each module (php file) at the top. Now all variables automatically become global by analogy with register_globals.

You need to do something like this:
$name=$_POST[name] ??
$page=(int)($_GET[page] ?? 0)

All corrections will need to be committed in human portions :)
It will be possible to test for errors on the demo version of the project available online.
Payment in rubles in any way. I prefer to pay in installments for the work done.
Leave a response. For details, you can write to me in the cart.