what i usually do and learned this from a guy down here is you cast out a big ass weight and then get your bait on another line and put it on a swivel and attach it to main line and slide the live mac down the live so it swims freely from the surface down to the weight and where are you from im not to sure where port shepstone is
Port Shepstone is on the east coast of South Africa
Yup I've heard alot about those rig's.
Over here it is called a sliding rig.
A lot of guys here use to get ragged tooth shark's but I've also heard that it's sometimes used for large Kabeljou (Cob).
As u said a large sinker is used.
Over here grapnel sinkers are used and after you have cast the sinker out the line is then retrieved to anchor the sinker to the bottom.
Then the sliding clip with live/dead bait is attached and then shaken up and down so that the bait can sink faster.
I think there is a free clip as well as a one way clip where the fish can go only lower.
Apparently you want the bait to be as close to the sinker as possible when you get a strike otherwise you can get broken off.