Hi Ivan,
I chose to strip the sheath in the local area of the pass thru eye. I wanted to make sure the eyeball had a good grip on the metal cable since polymers are known to creep even under low loads, especially at elevated temperatures. X-acto worked fine. Casual observer can't tell.
On a related subject, you might find via searching that the all aluminum eyes with the the blue anodised nut have been reported to gall and be very hard to remove. Maybe choose the ones with the four hole flanges.
One more thing. I only used one eyeball. That was for the prop gov. The throttle and mixture cables went through the stainless tube and firesleeve type penetrations since they were not at an angle to the firewall.