"I've got a lot of interference on the front left cowl."

#6 EGT probe (I can move it or get a shorter probe)
You could cut all but 1/16" off of a bolt that fits the hole.  It would be
held in place by the circle clamp that holds the probe.

#6 rocker cover bottom (no solution)  I had the same problem with the IO-550-N in my Legacy.  I cut the lower
corner of the Rocker Arm Cover off enough to clear the cowl.  There was
plenty of clearance to weld on a plate at the reduced height.  Remove the
rocker cover and pull the prop thru to get full travel on the arm.  Check
how much clearance you have to work with first.  I also removed the core in
cowl for a little extra clearance.  This one really had me worried since the
plane had been painted before I discovered it. Steve Colwell  Legacy