I used to run an MSD al6 ignition and the 1985 ford distributor with a steel gear and lemme tell ya, it will "work" either way and you will not harm anything by having the wires backwards. After my MSD burned out (curses), I replaced it with a hi-6 and was left holding those 2 very same wires in my hand and scratching my head. So I just said oh well and hooked them up. The car will fire up (meaning you did everything else right) but it will idle super lopey and funny. Then swap the wires and it will run like a champ.
If my memory serves me correctly though:
distributor is orange, brown and black/ground.
Orange=green
brown=purple