"Oh the front will never overcome the power of the less rear sag." You are correct that if one end is wrong, tweaking the other end won't fix it.
Maybe I should have explained that better. Assuming that the rear end is close to being right, that test I suggested gives a good idea as to whether one end or the other is sprung too light or heavy or if the damping is well balanced back to front. It's an easy test to determine which end needs to be changed.
In your case, I would expect the front to dive more and to dive faster than the rear which would indicate the springs are too soft and the damping is too light. the two should be balanced.
Stock springs or aftermarket doesn't matter what they say on the box. All that matters is how they work. What is the static sag and is it too much? If it is, try more pre-load. If static sag is OK then a soft front end comes down to springs too soft.
Adding additional oil decreases the air space and acts as an air spring and that may be enough to cure the problem but probably not.
Thicker oil will slow down the rate that the front end dives and will also slow the rate at which it returns. Too much damping makes for a bike that doesn't handle rapid changes of direction.
If your bike has too much sag at the rear then try adding more pre-load to get it right. It almost sounds like the front end spring rate is too low and the rear has too little preload but I may be misinterpreting your comments
But start with sag. at both ends. if that's not right, the rest will never be right.
