The Howard is a big step forward compared to any original, but the piston dome is going to be a puzzle. It contains the entire chamber volume, so something like a modern (heart shape etc. sunk into a full size dome (bore diameter). The surrounding surface area can be quench, or only part. Choose your own static CR. Some high end piston manufacturers may have already made shapes like this since the "Heron" (plank) chamber has been used in other engines.
The intake ports are 45 degree downdraft, all valves are vertical and parallel.
Howard intended stock rockers to be used, so the top surface has that bolt pattern, but I wouldn't use them. Not easy to find better, they're really long (about 3.41" adjuster to pallet), perhaps individual or paired pedestals?
