Just to complicate things a little, there is no such thing as an ideal ratio of weight distribution. It varies from car to car and even from one corner to the next for the same car.
As an example of some of the issues involved with getting the car to accelerate off a corner. You want to shift weight to the rear wheels on corner exit to allow better acceleration. But, if you shift too much weight, the front tires no longer have sufficient traction to turn the car and you find your exit speed is now limited by power understeer.
Here are just a couple of the things involved:
The power to weight ratio of the car. The more power, the more weight is shifted to the rear under acceleration.
The average corner speeds. At low speed the car accelerates much harder and transfers much more weight than at high speeds.
The vertical center of gravity. The higher it is the more weight transferred.
The distribution of roll stiffness. You can use a stiff front bar and soft rear bar to keep the weight more even on the rear tires so that the inside tire can contribute more drive, but then you have the problem of loading the outside front tire very heavily and you are back to the power understeer problem if you go too far with this.
While not an issue for a GT40, aerodynamic downforce is a major factor for most modern cars like Formula 1 (to the extent that a 200 mph car with open wheels can be called modern – another bit of rule enforced stupidity). The weight distribution changes with different speeds because you never get (and don’t want) perfectly even downforce front to rear at all speeds. (You always want more rear downforce than front downforce the faster you go).
This is just scratching the surface as far as what is involved in trying to select an optimum weight distribution for a particular car. In truth, you try to get a figure that gives you the best average results on the particular tracks that you have to run.