building a mild Daily driver 318

the motor im looking at now is a 69. that means the compression is 9.2 stock. (i googled it)
how much more compression would thin gaskets give me

Google? That's hilarious. Google doesn't know squat.

While the "spec" for the compression ratio may be correct, it is certainly not what they came through with.

Chrysler was known for terrible machining tolerances. Very tall block decks, big combustion chambers and so on. So, all that equals much lower actual compression than advertised.

You will be lucky if that engine has an honest 8.5:1.