A very small %of the gains is (caster and its effects on camber of the outside wheel in a turn are obviously the 'big' factor) actually from relocating the front wheel centreline forward just a touch, which is not quite as good as but similar to moving some weight rearward, and getting a more advantageous polar moment of inertia (very basically the closer most of the weight is to the centre of gravity the quicker the car can turn in. If on the other hand you put just 10-20 kg of weight on a specially made bracket so that it sits say 1-2metres forward of the front axle centre line, it'd have great 'leverage' o the car and make it want to slide wide/understeer more significantly. Obviously nobody is suggesting really rigging up such a thing, but it's a good way to visualise why shifting (some, and of course it's all relative to a specific car) weight back a little, or moving the front wheels forward just a little bit can actually have some positive effects.

Short version of all that, if you can manage it, increase the caster by moving the bottom of the strut forward. If you can't the caster itself is the majority of the gains, so do it however you can manage it, you only miss out on a few % of the total gains.