I couldn't give up and I think I've had success getting back. I'm waiting for the update to complete successfully, but I'll edit this post with what I did to make it all work. :)
As I initially suspected, my issue was a problem with HB...
Sure man take your time. There's no rush honestly.
Not sure if it's permanent, but at the moment, I'm unable to download the GPE RUU from here. Once that's available again, I'll re-download and try everything out.
Edit: Found a copy on my work d...
I also went with the non-rooted conversion.
Very weird... I don't want to suggest anything else. I pretty much shared everything I did.
I don't mind converting back to the GPE and going through the whole process again, but I'd have to do tha...