Chris,
If your boat has the original cables you are better off changing them out for new ones. It is impossible to lubricate a cable that long, I don't care what sort of fitting you put on it. The difference with new cables is amazing. Here are some suggestions:
-the way to do this is to make up a threaded fitting that "splices" the cables together, new to old, and slowly and gently pull the old one out, pulling the new one through. If your boat has the original engines and gears and controls, Sam's can tell you what the lengths are supposed to be. If repowered, they may be different! During the pull-through, you use a lot of silicone spray or WD40 or whatever to ease the cable going through.
-I used Panish cables (they also make controls). Teleflex are good as well. You probably have Morse. Use the SMALLEST diameter cable that you can use- the thicker the cable, the more friction (the frictional area between the moving part and the sheath is greater in thicker cables). Cables with friction-reducing layers like Teflon are better, I think.
-make sure that the cable is tied down every foot or so- any movement that is used up in cable lash will result in reduced motion at the working end, and screw up the feel of the control system.
-proper alignment of everything and anchoring of the cables at both ends is critical- the systems will NOT work unless this is done right. Don't assume that the old cables were installed and set up right- things drift over the years and get out of whack.
Shameless plug department: I got more help from Rob Panish at Panish Controls in CT than I could have imagined. Their products are great, and their customer support is better if that's possible. They make their own cables, and they will give you all the help you need setting things up. All cable ends are standardized, as far as I know, so you should be able to substitute anyone's cables for Morse.
When I first looked into replacing the controls and cables on Blue Note, I looked at Morse- the customer service and response by them were so God-awful that I gave up and went in a different direction. Morse have been acquired by Teleflex, but I don't know that it has done any good. Based on my experience of a few years ago, I would buy anything BUT Morse. Even though it was OEM.