I am NOT using longer shock shafts.
I have the 46mm Kyosho shafts in the box but they are too long and the piston hits the shock top cap before the spring platform bottoms out.
There is plenty of adjustment on the stock shock eyelets to get the droop balance you need with the kit 42mm shafts. I check the drop by using a ride height gauge to pick up the car until it just lifts off = actual droop measurement.
The other way of cause is to place the chassis on top of something to raise it off a flat surface (2 brand new wheels have always work ok for me) then measure the height from the surface to the axle centre.
The FS (and RB5 for that matter) are really hard to judge droop by eye due to the shape of the chassis edges ... even worse if trying to do it with the body shell on!
I am running 3B with 40wt AE oil as the basic set up, drop to 35wt AE oil when temperatures / track conditions dictate but it's 40wt 95% of the time.
2C pistons in the front can make the car feel a little calmer but make it less able to deal with the subtle bumps ... useful for smoother tracks with big jumps and / or high speed direction changes though.
Fab' ... that reminds me, you owe me some shock parts buddy
When you say -1 ackerman I take it you mean you are using the low height ball studs there?