I understand that the tecnhologies are vastly different, but I have a largish project that I would like to convert to WPF, and if there was a converter that could get it even 50% there, and show areas that it couldn't convert, then it would be helpful.
Short answer: No.
The technologies are vastly different. The quicker conversion is manual one.
The technologies are so different that any automated converter would really do more harm than good. Although you can write WPF that looks and works similarly to Windows Forms code, there is very little reason to do so.
You would be much better off migrating your application slowly, over time. You can use ElementHost and WindowsFormsHost to mix and match WPF and Windows Forms elements in the same application and same window. By doing this, you can choose which portions of the Application would benefit from moving to WPF, and target those first.
As you move to WPF, you'll most likely want to re-architect those sections of the application. WPF allows for quite a few changes in design, such as using MVVM, that are difficult or impossible in Windows Forms - and I'd strongly recommend taking advantage of the new architecture.