With the petrol engine removed, the pump used to provide the vacuum for the power brakes needs to be replaced by an electric vacuum pump.
The electric pump shown in the photo below is used for this ev.
The pump is supplied by http://www.metricmind.com vacuum pump type 70/6E
Alternatively a 12V electric tire air pump can be modified for this purpose.
The pump is connected to the original pipe from the brake booster