I love pieces like this. It was apparent within a couple of posts that all wasn't well and it wasn't one to chase but the fun is in treating it as a logic puzzle. Firstly eliminate the impossible then work with what remains and work out how it got there.
Did sunburst finishes exist in 50s Constellations?
I dont think so. I would say from the beginning of the 60's. '62 or something. When I think of the sunburst IWC's they also came from the 60's. But I'm doing this out of my head without any real research.