I understand your concerns. The problem with GCG is that it will probably reach the stones in the front of yr gb , but the ones in the back may not be reached unless you do a flush to eliminate the stones in the front and then the ones from the back will move front and GCG will crush them.
When you do yr flush use Olive oil with grapefruit juice, it less nauseous. A straw will also help you to put the mixture straight into yr throat so that you don´t taste it that much.
Hope it helps. The nausea may be uncomfortable but the results that come out of it by far pay it off