You are making it too complicated. Depending on the cam, you may or may not need pistons. Clevelands have a very distinct valve pocket. However those a 9°x4° and 9°x3° valves. In the picture below note their is no exhaust valve pocket. And unless you have a significant cam, you may not need an intake either.
The chamber come around 65cc. However you can mill them into the 50-60cc range. Like any other head swap, you need to calculate your compression and piston to valve clearance.
In this case, you may also want to make sure your quench is tight to take advantage of the combustion chamber.
In addition to swapping the head and manifold, you will need a 4150 base carb. And Cleveland rockers and new pushrods.