I purchased the Z-Line exhaust with the short stack for a 7' ceiling.  With the short kit I had to cut off about 3" of the angle iron & the lower stainless steel covering to get my 30" clearance from the stove top.  This required drilling the angle for the fan to mount on.   There was a transformer that had to be relocated for the covering to clean on one side.  The final install took three of us to mount the unit.  All this work seem worth it, the unit seems of good quality, runs quite and adds good LED lighting over the stove.