Hello. I am very curious what will be the outcome of this project. I am the proud owner of a 66 Safari 455/4-speed/4.11 Safe-t-trac. Of course, i was not luck enough to find one ALL FACTORY like you were. I had to buid mine from scratch. I have never seen a MT 73-77 wagon. I have owned a 73 GA 4-speed and parted another 73 GA 4-speed, a 76 Lemans 3-speed floor shift. The "parts" from the 73 have found a good home in my 77 GP, 428/4-speed. Here's the wagon. It was a rusted basket case, too. Hope it helps keep you motivated!
www.geocites.com/pontiacjeff
Jeff Ianitello