I couldn’t think of any reason to keep the frame pan underneath the frame now that the bearing guides are in place. So, I took the jewellers saw and hacked it away. Now the frame begins to look like a locomotive frame.
Inspired, I ferreted out the 3D printed ash pan and tested it for fit. Despite having accidentally sawn off most of the nubs on the back of the firebox that hold the rear up, the ash pan worked perfectly. It’s such a cool little part, I had to snap a photo, even if it is wrong.