At an absolute bare minimum if you are installing new Continental
cylinders you need to take them apart and have a reputable shop rework
the valve guides.

wrote:

ECI jugs have a really good reputation amongst the Lycoming crowd,
several of my local airport buddies are flying behind engines built
with ECI parts in both certificated and experimental planes and they
all love them. I dunno about ECI's reputation WRT Continental engines,
but one of my buddies had his C182 rebuilt using factory new jugs four
years ago and already had to replace one with less than 500 hrs on the
engine.