compression on pump gas

[69camarokid]

im getting a 350 that is 9.5:1 compression. im replacing the cylinder heads with the vortec style heads. my problem is that the way the vortec combustion chambers are designe, they raise compression. does anyone know ho much they raise the compression. and what is the highest compression i can run on pump gas 91 octane, this is goin to be my daily driver. thanks

[BlackLT1Z28]

What's the combustion chamber volume of the new heads?
If you figure that it's too much, you could get a little thicker head gasket to lower the compression slightly.
And I don't know the exact numbers, but I know the LT1 has a 10.5:1 comp ratio and the LT4 has a 10.8:1 comp ratio on pump gas.