I put mine in the bit of space behind the servo, the idea being to minimise the length of the fuel line in the engine bay. It works well but I'm considering moving it so I can fit an expansion tank. I can't remember exactly where I took the power from. If it wasn't dark I'd go out and check, but anywhere appropriately live with the ignition on I suppose. It is wired through one of these inertia switches:
View attachment 12138
which is mounted inside the car behind the driver's side glovebox. This is essential, because an electric pump will keep running after an accident even if the engine stops. These switches cost nothing second hand.
The fuel pump itself is mounted using two rubber cotton bobbin things to stop noise being transmitted into the car, but the pump runs so smoothly and quietly I'm not sure that's even necessary.
1975 Rover 3500 Engine by
Conrad Conelrad, on Flickr