Chip not really applicable...
Just because it's called a "Jetronic" system doesn't necessarily mean it can be chipped. In this case the fuel injection system is Bosch KE5-Jetronic...which at the core is a mechanical fuel injection system. Bosch added the EHA, controlled by an ECU, to fine tune the mixture for emissions reasons, but aftermarket firms figured out that it could also be used to enrich the mixture with an external control.
Also, the ignition system is completely separate with it's own controller, so in order to "chip" this engine to make more power, a completely separate third computer would be needed to enrich the fuel system AND control spark according to a new 'map'...that is why there is no chip for these engines.