Electric Seats

Just bought my Disco and whilst it was not advertised as having electric seats just found on further inspection that a previous owner has fitted electric seats to the original manual rails and wired up the back rest only (cut in to loom under both seats and fitted switches below window switches, tidy job)
What would it take to convert the whole seat back to electric and remove the manual adjustment.

PS

Are the headrests manual or electric on these seats before I wrench one off trying to lift it?

Just been informed by a mate that the front seats are actually from a range rover , so I wonder if this would be better in that particular forum?

i used to have a classic rangie with vogue seats in it, the easiest way is to cut the plugs off then hold each wire onto a battery, that way you will find out which wires do what, then just wire em into a switch panel, if they are the more modern seats with the control box on the side then power up the control box and hey presto