Yes, the top feed will drain out on a broken line. I went to a top feed on a 49 when I traded for a new tank that wouldn't accept the bottom feed on/off valve. It came with a new top feed sender w/filter sock. I had reservations as I didn't know I the fuel pump would pull through a top feed. It will.
I had to remove the fuel pump to carb line for servicing and the fuel continually dripped through the fuel pump into a catch can I placed under it until I hooked the line back up.
