Modify existing PHP file to suit new requirements - Simple

Team, Looking for a great freelancer to modify a PHP script with new additions of formating rules and additional requirements for a wallboard data gathering script. This should be a simple task, all the hard work has already been done. Just need to add our small changes for data presentation. Requirements will be PM'd to the awarded freelancer, these changes are not to affect the rest of the script. The awarding freelancer must allow us to test before payment. Payment is guaranteed as per my previous projects. The freelancer must be able to conduct small additional changes in coming weeks to ensure testing and shake testing ensures scripts reliability. Milestone payment will occur ONCE the initial test script is posted for testing. Thanks, Josh