What might my 360 CR be?

The ONLY way to calculate compression ratio is to do a .500 downfill and cc the bore just like a combustion chamber. Then, and ONLY then can you calculate the compression ratio.

FWIW a .040 positive deck height is no big deal. If you measure the depth of the chamber it's usually about .090-.100 and if you figure .040 out of the deck and a .039 gasket you are still at .090-.100 quench.

To do it correctly and keep the CR below 11.0:1 you would need the piston out of the deck .080-.090 and use a DISH piston to keep the CR where you want it.