Some thoughts on some of the standard design features to keep a replacement head marketable to the masses would be:

Must accept current Y-Block intake manifolds and gaskets.

Must accept current Y-Block exhaust manifolds, headers, gaskets.

Must accept current Y-Block valve covers and gaskets.

Must accept current Y-Block rocker arm assemblies.

If spark plug location is revised, must be able able to use with current exhaust systems.

14mm spark plugs.  Lots of these available in the various heat ranges.

Available ready to run with valves, springs, retainers, etc.

If aluminum, then heli-coils in the rocker stand, intake, and exhaust bolt hole threads.

Open for discussion.  If necessary, just start a new thread for the topic you have in mind or add to this thread any additional standard features.

Lorena, Texas (South of Waco)