I've fitted C6 seats to my 78.
Initially kept the electric mechanism but this rasied the seats approx 40-50 mm higher than original. Not too good for driving.
Ended up removing the electrics and bolting the original seat tracks to the seats. Sits a little higher than the old seats but they were shot so I think the height they are now would be close to a standard seat height. Kept the the pumps for the lumbar and bolster support though.
Great seats - very comfortable.
Robert