As far as I know, the Sierra 18-7350 "square" fuel pump will fit in there. Lots of other options too, if you want to get creative. Like the Mikuni pump, or Briggs & Stratton. Here’s a Briggs pump that I installed, but it was a bit more than a "little" creative by the time I fabricated a mounting bracket. And it was a bit tricky getting the shroud on when I got done.
