John - It depends on which post '57 Y distributor you have - early or late. This picture shows the upper rotor shafts of the two types. At upper left is the early arrangement with a fixed point cam and the two rectangular slots for the advance mechanism. At lower right is the later type upper rotor shaft used in the housings with the "three lobed" shaft cover (like the '79 donor distributor you've got in hand). If the housings are a match, just start swapping parts.
If you have the older distributor it can still be used - by modifying the upper rotor shaft to remove the point cam and turn down the upper tube to fit the reluctor. The one below has been altered to accept the reluctor and carry it at the proper height. The fixed cam is hardened, so you'll need to grind it down a bit to save machining time and also save some cutting tools.
If it turns out that this operation is what you need - send me a PM with an email address and I'll send you a PDF file print to take to the machine shop. The link below will get you to the drawing I made of the wiring schematic. This one is made to utilze the Duraspark II controller with the "blue grommet"
http://pages.sbcglobal.net/mshum/HoLun/WIRINGSCHEMATICT-BIRD1.jpg