After looking for a while for a deal on original F1 upper shock mounts, I gave up and bought a pair from Speedway. The original curve at the bottom didn't fit the height of my frame with the front spring notch, so I followed the method described in the Bishop/Tardel book. First I cut off the curved part of the mounts below the first hole. Then I did a little shaping with the grinder. To position the mount correctly, I drilled the first hole and bolted the top part of the mount in place. Then I marked the position of the second hole. I drilled the second hole and after chamfering the end of the lower piece, I bolted it into place. Then I tacked the pieces together. Here's a shot of the mounts after welding and grinding. And here's the left side installed.