I just finished doing my valves, I never felt that the carbs were in the way at all.
I did not remove the radiator, but I did take out the mounting bolts and let it hang on the hoses. This is not for clearance to get to the valves but for room to get the valve cover in and out. I can see where it would be easier to get the front valve cover in and out if you took the radiator out completely. Half of the job is removing all the stuff to get to the valves.
It is not a difficult job to do, but it is very time consuming, this is why it is so expensive at a dealer.