Black Kat- There is know perfect tire combo that works on every surface or even on the same track everytime. I could give you my setup and tire combo for our asphalt VHT treated track and it is more likely to not work than work for you.
If you race at only one track and they treat it the same everytime and you have close to the same number of car running each race day then you will come up with a tire combo that usaully works.
But if it rains a few days before the race, is windy and track gets dust on it, you have a low turn out , you have a high turnout, or they treat the track with different traction additive, they treat the track heavy or light with additive then the track can be very different requiring different shore tires.
IMHO it is always best to run the hardest tires you can and still get the traction you need. If you run different compounds front and rear and you run a main longer than 20 minutes or have a real aggresive track surface then you will want to cut your tires bigger on the end of the car that has the softer compound.
You should always be checking tire wear during your qualifiers so that when you get to the main you can figure out what diameter you need to run and how much bigger the softer end will need to be to keep you tires at the IDEAL size for the longest amount of time in the race. If you do not understand over/underdrive then you will need to so that you knwo how to expect the car to handle at the start of your main with slightly larger tires on one end, will it understeer or oversteer??
Also don't throw your car out on the track first thing in the morning and expect it to hook up and handle on rails right after they treat the track, it will take some time (cars on the track) to get it to come in. Many guys go out then the car is not right and then they start making changes one after another and then when the track "comes in" they are way off in there setup and have new problems to deal with.
Di d you try 40F/40R ? I ask becasue I see you were at 42F/40R
I hope this helps you.