Having been in the printing business for too long, I have had the chance to get all the "line cameras" I would ever want and passed on them all. The dolly you refer to is most likely the track the vacuum frame runs on along the floor. If I remember correctly, when I was in Ansels' darkroom in 1982, he had basically converted a similar process camera into his enlarger. He had done quite a large amount of work on the projection end with dozens of lights to illuminate his 8x10 negs and I think that he had the other end of the track holding the paper with magnets and possibly a vacuum apparatus. The negatives were projected horizontally and he could move the paper forward or backwards as to whatever enlargement he wanted. It was a beast and he dodged and burned like a conductor at the symphony. If you have the room, a large room, then if one had the time it would be a hoot to fix one up as the ultimate enlarger. 20x24 prints from 8x10 negs look great and a process camera would handle them easily. Just be ready for a large bob-tail truck to move it.