Would be easier and might have been cheaper to get the complete arms. Just did that on the 70 - $69.96 each side, done in 30 minutes.
You'll need to cut a piece of pipe that will just wedge between the "ears". You'll need to keep the "ears" from bending in. Install the shaft and thread on the ends. Center the shaft between the ends - takes a bit of "messing with" because of the vastly different thread sizes. Thread the ends down tight then torque to the recommended rating (no book here in front of me so I don't have that figure). Make sure the shaft can still move fairly freely. The new arms I used -once lubricated- could be moved easily by hand with the shafts lightly bolted into the shock tower. If I was doing it, once I had the fit I would loosen the end caps and use red loctite and retorque to make sure they didn't back off. (and if I ever went back in, toss arm, shaft and all in the trash). I set the ones on the Falcon (many moons ago) a bit loose for easy and smooth front end rise.
It you don't use the spacer, the ears will bend when you torque the caps and the shaft will bind in the caps.