Many years ago my Dad made some modifications to his Northern based on the Wabash O1 4-8-4.
Unfotunately, after he passed I let it go to auction and regretted not keeping it. Reading this thread inspired me to build one like his, and I was able to finish it today.
I added a steam dome that I found on eBay that fits well. The only other modifications were to modify the front bell to bend the arm upward and I clipped out the back cab windows for a train crew.
The decals were pieced together from various sets I found on eBay as well. Here is a video of it running: