I wouldn't say that is 'overloaded big time'
A 2lb test curve rod is well capable of casting a 4 oz lead. Maybe not a long way, but well capable of it nonetheless
It depends on the action and quality of the rod, casting style, line weight used etc, and the actual distances and weight of bait etc. You are talking about. I class 2.75s well heavy. I use 1.75 to 2.25 for the majority of my carp fishing. You can punch a 2.5 ounce lead a mighty long way on a 2.25/ The actions are crisp too, but you have to wind in and lean in a hell of a lot at any range, obviously
All depends on what u are comfortable with i guess, but I would say 90% of carpers I have come across have been overgunned for their situations