OK, well this is how my gas system works. Its not an impco setup, just the average setup.
There is a wire that is connected to the gas converter, this is what controls the converter (On/Off) its a simple 12V signal.
There is another wire connected to the fuel pump relay.
Every time you turn you ignition on, the fuel pump is run for a few seconds to get the pressure up. The gas is connected to this wire so that when you are about to start your car, the converter purges, allowing gas to enter the intake.
When you start the car, the pump stays on. This also gives a constant signal to the converter.
The only difference between having the car in ULP mode, or LPG mode is whether the injectors are firing or not. In the LPG mode, the injectors are shut off, and the converter signal connected, and vice versa.
All the wiring of the gas system is identical from the CFI to the MPI, and you don't need to alter it. The only wire you will need to re-connect is the injector shut off wire.
Relocating the converter is easy. Get a mounting bracket from a mpi from the wreckers. Install it so that it is on the intake manifold side of the engine, near the washer bottle.
The copper pipe running to the converter can be bent and moved easily. Connect the signal wire to the solenoid as it was previously. Then all you need is a mixer for the mpi intake, and the pipe going to it from the converter.
Itís late, I hope this is making sense.
CAUTION: Slippery When BOOSTING!