Add headrests to split bench '69 Barracuda

Trying to keep this car all original but I want headrests for safety issues. It has the front split bench with a fold down armrest. I have seen a few headrests for sale for '69 Barracuda, but how do I install them? Are there kits available? I have searched for a while now on this forum and the resto places but I cannot find anything...
Thanks