when I used to fish in Timaru city the main spots I would fish where off the rocks around by the port,The beach south of the breakwater by the petrol tanks and the beach by the Smithfield meat works, Would mostly catch Dogfish and small school sharks but occasionally caught the odd elephant fish and conger eels Also hooked a huge stingray around Caroline bay, As I said earlier I Found the fishing to be more productive North and south of the city at places like Connolly road and St Andrews so mainly fished there rather than the city.
4oz Pyramid sninkers are fine in calm conditions and off the rocks where there is lots of snags but really if fishing off the shingle beaches breakaway sinkers are better.
what diameter is the 25lb mono? this is more important for casting distance than breaking strain. ideally you want 0.40mm Which is about 20lb. The cheap rod should be fine just don’t overload it id be using 3oz sinkers rather than 4oz. There are verious other ways to improve your casting distance such as clipping down your baits,getting a reel with a long cast spool,using braid etc. But really as long as your clearing the breakers you should catch fish.