:)Hi Liam
I have early model Commodore buckets fitted to my FC, they have removable headrests and fit very well. I used the standard Commodore floor mounts to retain the slide mech. etc.
I just made up two mounting brackets for each seat, this run length wise, under the existing commodore slides and have plates attached front and rear to allow the bolting to the orinigal outside bolt holes in the floor. The inner mounts near the tunnel are exact copies of outside units but you have to drill the floor and place rectangular plates under floor to spread the mounting load. This install was approved by an engineer.
Hope this helps, sorry for being long winded.
John.M