318 La with 360 heads
Get on jegs or Summit and get a CC kit and read the directions.
Or...
If you have something that measures Cc's or ounces and you can convert to cc's... use a cd case, drill a hole, grease the head deck to seal the case cover, with valves and spark plug installed..then pour starting with x amount in measuring cup/tube/wtevr and measure what's left after chamber fill with all air holes out...convert and that's your chamber size.