The fuel connector used by West Bend and on the WB made Elgins is unique, they are not easy to find. (I see 50 motors to 1 connector…) The neatest conversion I’ve done is using the later WB/Chrysler style, however the motor (male fitting) was something I scrounged and I couldn’t tell you what it came off of. As you noted, many people simply jam a hose on the male fitting or use a short hose as an adapter to an OMC or Mercury motor-end fitting. I would suggest getting the motor running and performing well, then figuring out what to do about it.
Other than the aforementioned bendix gear, they are fantastic motors. I’ve come to love my 1960 WB 12hp (mechanically the same as your ’57) so much that it has supplanted my ’55 Johnson 10hp as my go-to motor for daily use on my 12′ DuraNautic. It’s as quiet and smooth as the QD, more fuel efficient and has just a tad more power and speed – plus I love that funky "George Jetson" styling! I did the OMC coil and condenser swap that I outlined in the Tech Tip on my website. The original impellers seem very robust, but if you need one I think they cross to the Mercury/Force # 47-F901065. Fuel pump diaphragm is easy to make or can also be purchased from Mercury, # 27-818043A1.
West Bend/Elgin fuel barb
WB/Elgin Fuel Connector
I did a short video last summer on my 1960 West Bend, if you are interested it can be found at the following link:
https://www.youtube.com/watch?v=XRNml-eKJV0