There I do not know. The 1966 Buick Riviera, the Olds Toronado, and later the Cadillac El Dorado, all shared their own unique front wheel drive X frame that was different from all of the other GM platforms. Because of a lack of trans tunnel and drive shaft hump the seat will probably have to be modified.
I used to buy the interior out of Buick's and Cadillac's and install them in my Impalas when I wore out the originals as they were more up scale and comffy. But I used the rear wheel drive variant of the B-body (or B and D body with a Caddy) as they were a direct bolt in.