Basically, you need two cars. I know it's what people want:
A street car with high efficiency and good mielage, but you should also be able to race it occasionally. This won't work out really well. Period.
This is because of the two different useages you need:
For a street car you need high torque at low RPMs, for a race car you need high power at high RPMs.
For high torque you need heads with a smaller intake runner volume to get a higher port velocity and better mixture of the fuel and air, but you don't want runners too big, they will kill the low end torque because of the loss of the above mentioned port velocity. For racing use you need a high volume of mitxture, which is only obtainable by having big runners. Same appiles to carb and fuel injection.
An engine is basically an airpump. A racing airpump needs to pump a lot of air in a short time, a street airpump has to pump a small amount of air in a longer time (for efficiency). There are compromises, but a compromise is never the best of both worlds. You might get just about affordable mileage and track speed of under 15s. But you wont get 25mpg in a 12s car. Many have tried that
One way to get about this is of course quite simple: If you really only want to race it occasionally get a set of cylinder head studs and buy two different top ends and a timing cover which allows for cam change without lowering the oil pan. Then you can change from street to track and back in half a day and have the best of both worlds. You just need a stout bottom end, which won't hurt a street car either.
In a Camaro you have the space to work on it nicely. And don'T forget: There's more to ETs than the engine: Suspension, tires, weight, trans...
Just my thoughts...
Max