The correct style of heaters for a '53 are below (the Air-Flow would have an inner dump door also shown). That being said if functional either of yours would work, personal choice prevails.
https://www.flickr.com/photos/advance-design_parts_co/8129448404/in/album-72157631868452754/
https://www.flickr.com/photos/advance-design_parts_co/8129312977/in/album-72157631868452754/