Can someone give me a schemetic showing connections for a 123 Electronic ignition and showing the relative oil pressure switch.?
One other question. I have an electric connection to the Solex 26/35 carb. Item Nr 19 on an IPB of this carb. Where does this connect?

I don't think 123 ignition has any wiring for the pressure switch, which is on the side of the block and totally unrelated to the ignition wiring.

However, on an original car that hasn't had 123 fitted, and is running as Boulonger intended, the wire between points and coil, and pressure switch and wiring loom is in the same bit of rubber tubing which is clipped into the fan cowling and runs out of the front of it through a grommet and upto the wiring under the headlamp bar. You may find that when pulling the wiring out to fit the point-less 123 that the wire has just come adrift from the switch, or maybe disconnected where it joins the loom under the headlight bar.