FreeGameDev

So as a learning exercise I'm taking a very old and abandoned project and seeing if I can update it to more modern standards, to keep my C/C++ skills from atrophying and to force myself to learn some of the newer language features.

What is the correct/accepted way to do file headers and read me attribution when you are making completely new files and code but still based off old code?
In the end, there will probably be no direct code from the original project, but it is still a derived work of the original, so it will fall under the same license of course (GPL v2) and I want to make sure it's all attributed correctly.

Is it acceptable to copyright it under me and just state it's a derived work? or is there some common format people use to show that it's new work built upon the work of others?

I realize nobody here is a lawyer, I'm just curious what others' have done in similar situations.

I've fixed up a few projects but never really done that. Usually I've left the filenames alone or simply renamed them. If they were largely based on an existing file I might copy whatever comment they had at the start. I don't worry about attributing individual files usually. I generally look at the code as a whole and make sure the documentation mentions the various contributors.