Install Ronsen hammers made with felt from Bacon Felt Co.  Have a
qualified tech measure the action parameters to order the optimal
overall length and to bore them correctly for each section.

Have the hammer weight matched to the piano action ratio and graduate
their weight.  Have the action evaluated for optimal geometry at the
same time -- it will make a huge difference in performance.  This is
a specialized field not understood by many techs, let alone a DIY'er.

Jon Page