Paul, sorry if I have given you a bum steer with this.
The
Bristol parts list doesn't actually show an electric pump on the diagram, but I now see another pump appears in the components list, but there's no indication of what it is.
There may of course have been another later parts list created, but this is around the time when Bristol started to get cagey with detailed information about it's cars.
Unless you're entering your car to be judged in the Bristol Owners Club concours I don't think you need to worry about having a Facet pump. I know other Bristol owners who have them and you will find that most Bristols that are still on the road today have non standard parts fitted, particularly when they are parts that are out of sight.
Just as a matter of interest, where is the SU pump located on your car?