I have an '81 my self- and I too have been frustrated by the carbs. As to replacing them, I have been looking for a reasonable set of '82 carbs. While I haven't done it yet, It is my understanding that the '82s will bolt right on. Also the '82s have removable jets and they have the same carb spacing.
IF you don't have the accelerator pump hooked up, this is certainly a reason for the bike to give you a lean surge at low RPMs when you open the throttle.
I went to look at a used '81 for sale, and the owner had replaced the carbs. I wish I knew what the carbs were from- but they had the newer small pods on top. he said they were basically just a bolt on except he had to reverse the choke bracket- He didn't know the source of the carbs, but was told they were from a late model Honda.
If it helps you any, I have mine (with the original carbs) working very well. I threw away the vacuum on/off and got a used but working diaphragm for the accelerator pump so it works fined. Mine pulls fine from 1000 rpm to 10,000. My only problem at this point is that I have a very tiny gas leak I can't find. I can Smell the gas, and I can feel a dampness on the float bowl of the #1 carb when its on the side stand. I'm sure I'll find it when I tank the tank off the next time. I'm waiting for some fancy new plug wires right now, when they get here I'm sure I'l fix the leak at the same time. But the good thing is the bike will run great with the stock carbs!