Brake swap to -64 Dart

HI.

I am swapping my -64 Dart´s original 9" front drums to single caliber -79 Aspen disc brakes. All orher parts I have except upper control arms with bigger ball joints. I haven´t been able to locate any -73 to 76 Dart control arms so far. Only in ebay aftermarket ones made of steel tube. Now I wonder do those tube arms really 100% sure fit? They are quite expencive and wouldn´t like to purhace ones if I am not totally sure they fit. Does any of you have any experience? I thank for any answer.

Pasi
Finland