I fitted an electric pump on our Bis way back in 1991 . The original pump failed so I just got a Morris Minor electric pump out of my garage and installed that to get me back on the road.
The problem with the Bis is that the pumps are "sealed for life" units and you can't do anything with them. Most of the pumps fitted to the air cooled range can be refurbished and it is normaly only the diaphragm that fails . If you carry a spare it is quite an easy roadside fix

Having said that I have got a blanking plate from Cos and also have a new electric pump just in case I feel like using one.