I believe thats what the factory did. I have it on mine and its the same piece just turned a different way.
I would have to talk to a friend of mine about it again however I do remember there was a left and a right shock mount. That I'm not 100% sure of but I do remember talking about it and being shown a distinct left and right plate.
On the other side of the conversion, you have to make sure you have all the missing chassis cross members to make a staggered shock mount, you would need this from a donor car.
Only factory optioned staggered shock chassis received the cross members needed to install staggered shocks. A lot of people do not realize this they think if a car is a Mach 1 or a fastback body style they all have the same cross members under the trunk floor this is not the case.
The competion suspension package included the mounts for the rear sway bar inside the gas tank mount and the rails, and also included the extra cross members welded to the chassis under the front of the trunk area.
Now all the cars were stamped with 3 holes for rear shock access, 2 are used for the regular shock mounts the third was used in place of one shock access hole for the staggered shock mount. So a lot of guys are suprised on a regular suspension car they pop off the rubber cap over the third hole and there is just a big drain hole there with nothing under it, because the car was never equipped with the staggered shock mount crossmember.
It's funny cause up till a few years ago people would cut that section of the car out on a staggered car and just chuck it out, they didn't know the importance of that area of the car for the option. They just assumed all the cars were setup for staggered rear shocks, and you just needed the lower mounts, that is not the case.