I don’t think your original pump is rebuildable so a good replacement would be one of the the small, square pumps which were used just about everywhere. The Sierra P/N is 18-7350.
If you use a square pump, the fittings may need orienting to your motor so the following link will take you to Leeroys Ramblings which shows how to do it.
http://www.leeroysramblings.com/Rebuilding_fuelpump.htm
http://www.go2marine.com/productcenters … -2_794_0_0