great! the question is becaus of enginechange and the loom.
citroens loom to the gti/mi16 (xu9jaz/xu9j4) only needs the +12v feed to work. conversion is pretty easy.
I assume the revcounter is at the coil as well
Yes, the revcounter is at the coil.
And yes, you should be able to reuse much of the wiring, but if I think it makes sense to replace the green connector with a water proof type, or at least replace all the tabs and sockets inside (provided the shells are still good).
In this diagram, the connector is MC2 (right side of the image).
http://www.matrasport.dk/Cars/Murena/vault/murena_el_diagram_1of2.jpg