Thanks, to add:
King Mackrel, aka couta/cuda/serra/kingfish are not super strong fish but are very fast and their size is often judged by the amount of runs they make, most fish in summer are in the 7-15 kg range with the odd 20+ thrown in.
The Natal south coast gets some crocs in winter as well as the high points off Zinkwazi and the wrecks off Richards Bay, generally caught on bigger baits like kawas/bonnies. Shad and mackrel are a favourite for couta but dead sard amongst the livies sometimes does the trick?? In Mozambique a lot of shoal couta between 3 - 8 kgs are caught and the smaller ones (darts) can become a nusance, bigger fish (15+) can be found on the deeper pinacles but are not as plentiful as the shoal couta - dead baits(halfbeaks/sards) are used more as live baits are harder to come by.
Remember to balance your terminal tackle to the rod/reel/line - if for example you are using a Shimano Speedmaster IV(excellent couta reel) with 20-25lb mono, there is no use to have a #4 power swivel (76kgs) when a #6 (46kgs) or a #8 (28kgs) will do, the same with wire - #4 is 40lbs, unless you are fishing for crocs there is no need to go above this.
The most important thing is your reels drag - it has to be SMOOTH!! couta take long blistering runs and a drag that is snatching WILL lose fish.
Your setup is a personal preferance - I prefer 8' or 8'6" rods, some guys prefer 7' but I would not go shorter than that. IMO these are good combos: COUTA LIGHT - Kingfisher Snoek Ski/Elbe Powercurve and Daiwa SL30 with15-20lb mono COUTA ALLROUND - Kingfisher Dorado Ski or Cuda Ski/Elbe Cuda Pro and Shimano Speedmaster IV/Shimano TLD15 with 20 -25lb mono.
The rod in the pic is an 8' Elbe Powercurve with a SL30 and 20lb mono bending to a shoal couta.