[CSX 4027]

Cut heads are great for compression.
Dished pistons and valves are not the way to go.

If it were me, and I have had both street compression and 12:1 in a Cobra....
Just go the 12:1.
You will be happy.
For the amount of time you will use the car and the fact that you will have a 42 gal tank, don't even thing about pump gas, not worth the issue.

But if you need..
Pump gas
Iron heads 10:1 or less
Aluminum 10.5:1 max

A lot depends on other build issues such as static compression and other things I can not explain.
But, my engine builder partner can if you need.