I can't help except with a couple ideas...
Stroll through a yard and seek an MII or Capri with the same rack and look, or find a set of original hoses. The ends should be different sizes and will only go on one way.
Last resort, hit the library and look for a Mustang repair manual.
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Sorry, just saw where you are hunting from! Did any of the european fords use the same rack or pump? If so, you can compare with them.

Current fleet (subject to change w/o notice)
\'49 GMC 3/4-Ton , 60 Austin Healey Frog-eye Sprite (some assembly required), 2011 Dodge Avenger, 2015 Jeep Cherokee. No, they don't all run.
My other ride is a (B737)no, (B767)no, A320.... Update... was Embraer E190, now Boeing B787.

Knowledge is a wonderful thing, but ignorance means you don't know you can't do something.