While not trying to talk you out of a new SU or Hardi pump, I can help you fix what you have - to keep as a spare.

That pump is a 'Walbro' type pump, and they were a very popular Universal replacement in the 1970s and 1980s. They were used extensilely in marine applications as well. They are common on eBay, with many different parts companies like A/C and Aeroquip names on the body.

There is a rubber bellows at the top that has no doubt disintegrated. The only place I have found that still stocks a rebuild kit, is here:
https://www.autoperformanceengineeri.../bel_pump.html

Buy two kits, as this REALLY is the only place that stocks them.