I have one gun that is CYL/CYL, and have made some longer shots with it, but I have shot it extensively over the years.
However, as I get older , my reflexes are slowing bit, and I have a a bit f difficulty reacting as fast as when I was younger, so getting both hammers cocked and swinging smoothly on a fast flush , I sometimes do not get the shot off or the bird is a bit further, so I prefer a tighter choked gun.
IC/MOD work well in that instance for me, but I am happy with CYL/MOD or CYL/FULL like a couple of my guns are choked.
Back in the 60's when I started , most of the guns for the N.A. market were choked IC/MOD for an upland gun.
However, if you are going to rechoke a fixed choke gun, that is FULL/FULL, just taking out the first barrel to IC and leaving the second barrel as FULL should work perfectly for you, IMO
That is what I would do if hunting over dogs.
Cheaper as well.
Cat