No in 1968 the stock ADVERTISED ratio was 10.0 , but what's a half point between friends. The ACTUAL ratio was 9.3 , if you were lucky , that's why I am asking what you have vs. what it appears you are ASSUMING.
Do not ASSUME when it comes to the 383 .
To get 10.0 in a 383 with the open chamber head you need a 79.5 cc combustion chamber with the piston poking .020 above the deck with the .021 shim gasket and a piston with NO VALVE RELIEFS. With a closed chamber you would need zero deck, .039 gasket and I'm going guess something around 72cc for chamber volume .