IO-360 break-in and oil recommendations?

I got the same advice on my Arrow IO360 from Poplar Grove Airmotive
with a recent TOH - 50 weight until consumption stabilizes, then
multi-viscosity. I have chrome cylinders so it took about 30 hours to
stabilize.

They told me to fly it hard - 70-75% and stay low (5000 ft) to
maximize manifold pressure. I used 100-150 ROP to keep the cylinders
cool. First trip was 30 minutes orbiting the Class D airport at 2000
AGL with agreement from tower just to make sure I could land in a
hurry if something came loose.