John:

**First, quit running LOP. Try high MAP, low RPM (oversquare, like 27", 2200)
for a few hours. **

The recorded internal cylinder pressure data suggests that that is an ill-advised concept.   High MP, Low RPMs when ROP results in exceedingly high internal cylinder pressures and, to make matters worse, they are closer to TDC.  This is NOT what you want during breakin.

What you want are high MEAN pressures (high HP) with cool CHTs (LOP and the peak pressure further form TDC.  This seats the rings using high mean pressures but with lower PEAK pressures out of the choke area.  Placing high peak pressures high in the cylinder in the choke area is not what you want to have happen.  We break in engines at very high power settings (above 80%), LOP.  This works best to accomplish quick ring seating in the area of the cylinder where it is most advantageous and keeps them from being over heated.

Walter