Engine number on a Chevrolet gives me riddles?

Good afternoon. I bought a 1972 Impala. The engine number is K0407CGO. Now I would like to know whether it is a 5 litre or 5.7 litre engine and whether it has hydo-pulses or normal valves. I would like to adjust the valves and the ignition. To do this I need adjustment values. Also the pins on the flywheel to adjust the ignition are a mystery to me. Do I give back from the middle zero by 10 degrees and then half again or how do you do that? Is it important to know what kind of engine I have? Can someone help me? Thank you so much. Micha