It will probably be easiest to create your own copy of the built-in report. And maybe make it into a MVC version, while you are at it. 😉
Otherwise you will be looking at overriding both the code behind and the template. And then you are already well on your way to your own copy of the report.
I will do as Stefan say and write your own version of it.
I have written a blog post that describe how to do that, it might need some small changes after the new UI but I think it still works
However, I already created a custom report before, the problem is that the LinkStatus report is kind of a special one. Since it's not found in the Reports folder but refers to a 'BrokenLinks' page/method that resides somewhere else
Use DotPeek or ILspy to decompile EPiServer.Cms.Shell.UI and find the LinkStatus report in EPiServer.Cms.Shell.UI.Controllers.Reports.Internal.EPiBrokenLinksController.
I have some experience in creating new reports for the Reports-functionality in Episerver 11, however, now I have a request to expand the functionality of an existing report (LinkStatus Report) with an 'export to xls' feature.
Anyone knows how to extend the funcationality without hacking into the CMS.zip file to modify those webforms?
Thanks in advance