A few things here to take note of.
Nitro methane produces its own oxygen, if you hit a drop of it with a hammer it will explode.
TF FC engine are making around the 10000hp mark that approx. 1250hp per cly of 62ci.
An engine will turn approx. 440 time per 1/4 mile run
You cant lift and trip out of the buckets the fuel require in a run faster than it uses it.
Next overlap is use to get the maximum charge into the cly and has nothing at all to do with cooling,
They generally run 3 fuel nozzles on of which is directly sprayed into the combustion chamber the other two into the intake port,
The angle of the headers are up and layed back they also plant the car to the track and if you loose a cly it make the car turn that's how much engry is being lost.
As for cam timming if you advance your timing you will get quicker ET
Retard your timing you get faster speed as a rule of thumb
Now a blown engine dose not need the exhaust to be particular great as the incoming charge is being forced into the chamber,
A NA engines looses HP in the exhaust if its not right, the exhaust flow helps the scavenge of the cly spent gasses to be removed from the other cly.
If you look at a NA drag car normally a 4 into 1 system at around primary tube length of approx 30 inches give or take.
Now remember the roots type blower was before being hot-rodded onto the top of an engine was a GMC scavenge pump use to remove the exhaust from GMC diesel engines.
Short stacks where used on blown fighters as there is no looses and remember they where super charged.
Also even thought an aircraft engine is relatively not a high rpm engine its cly area is large and as such the gas is slow to be removed. Most aircraft exhaust system's are built for cost and resections of space is a limiting factor.
Yes there also was a power advance from the spitfire but more from the mustang heat exchangers due to the heated air and the velocity increase sorry I cant remember exactly how much it was but it was an increase.
Cheers