Hi Tim,it is correct that the furflex seal the door but that is mainly for draughts.
There is another soft rubber seal that glues along the top of the door,and extends part way down the front to the door hinge and part way down the rear of the door to stop water coming in.
Martrim ,Small Ford Spares ,Woollies and other suppliers should be able to fix you up .
It is a specific shape to fit up to the roof,so don't buy a square section,i will try and sort a photo or dimensions when i can but the suppliers should know the one thats needed
On the bottom there is a large rubber moulding that screws onto the chassis and then traps down the side of the chassis with the sill fixings, repro ones are available at about £12 ea.