Actually the CEV speedometer in your link is the Italian speedos that came on the first ORIGINAL Pacer from 1976. They will fit fine in the plastic dash or bullet headlight (not sure what housing you're using.)
They may have used these in 1977 too but all other pacer's used the Huret. The're about equal in quality. I have both myself. Little differences are a textured drive cable for CEV (huret is smooth. this has no function just soemthing i noticed) and the cable caps on the CEV which attach to the drive and speedo itself, are black plastic while the huret is metal.
I would get a further opinion but I'm going to say they are about exactly the same. if you;re not in a crazy rush i could proably check it out for you tommorow.
In conclusion, using a CEV would only make your bike more Italian haha and you wouldn;t be straying from stock pacer equipment. I'm assuming you have a Super SPort? or is it the standard step through model? I'd love to see you post a pic of your bike! my 1980 pacer (currently 90% restored ) has the huret and the pacer i plan to assemble this summer will be using the CEV. pics will be posted in the future! whew.