Your set up is very similar to the one I was running. My 383 had the original flat tops (no valve reliefs) and a .501 hydraulic cam. I added some 84cc Eddy heads, swapped out the cam to a crane solid .540/.560 lift. I trusted a friend(?) when said there was no need to clay it to check for piston to valve clearance. Guess what? It broke badly. The valves were slapping the pistons til they broke in 3 cylinders and bounced around a while until they finally settled into the valve seats - sideways. It was a very expensive lesson. Check for clearance - assume nothing - verify, then check it again.
