I gave it some thought and realized that the GT40 was substantially lighter than the other two cars so I set out to check how much lighter. In fact I decided to check some of my other VS6075 cars for comparison and came up with the following information:

The columns are self-explanatory aside from the final column titled "77". This column shows how far off a weight of 77gm each car is. Why 77gm? Well I found the average of the lightest and heaviest cars and this came up to 77gm. So if I wanted to reduce the cars' performance differences by making them all weigh 77gm, I would have to add or remove each one's weight difference by the amount shown in this last column.
What do you think about this? Would you agree to a minimum weight of 77gm for our VS6075 class?