The first picture like you posted is of 72 on up forks. Which are the ones that your bike should have. There are two other stlyes, the older type like I have in my bike have a vertical flange with 2 bolt holes in it. Those are forks from 71 on down to 69, and require a different typw of arm to mount the caliper. The arm is fairly large and flat uses 3 bolts to mount it to the fork leg. And the last style came in 79 I think. They are easy to identify because the caliper bracket is cast to back of the left fork leg, and they also have a ribbed section on the top where the seal goes.
Hope this helps,
Travis
P.S. I have pics of my early forks if you want to see them, but I have to wait to post em since I'm at work.