[Blas]

The main power feed from the solenoid to the cabin of the car is a 4mm wire.
That wire feeds EVERYTHING electrical on the car.
Using US terms for reference:
6 ga is 4.11mm - so you have little less than 6 ga. wire feeding all your electrical services on your car.
6 ga wire is good for.~66-85 amps. (Remember: You ALMOST have A 6 ga wire feed) Others have done it successfully. The question is: "Are you feeling lucky"
Add the fuse or circuit breaker too. (80 amp)

Some Reference Info:

BOSCH Radiator fans 15A each: = 30A Total.
SPF supplied headlights high beams (60W/??W) = 5A each side/ ??A each side = 10A Total/ ??A Total.
Aftermarket Bulbs: 100W/130W = 8.33amps or 11A = 17A or 22A Total.
Brake Lights: (for halogen bulbs) = 4A ea side = 8A Total,
Std Tail lights: = 1A total.
MSD Ignition Module @ 5,000 RPM: = 5A Total.
Canton Accusump solenoid: = 1A Total.
Holly Red Fuel Pump: = 7.5A Total.
Hella Twin Supertone Horns: = 72W = 6A Total
Instrument Gauges: 7 Bulbs @ 2.2W each = 15.2W Total = 1A Total