Okay, let's see if I have this right. You want to re-engineer the whole gun just to make it look cool... Okay, if that floats your boat. A major modification like that would only be done to improve performance. This will likely degrade performance.
That said, if I were doing it I would move everything forward and then extend the bolt piston rod. This will maintain the same piston chamber volume as before and the 1-2 gas adjustment feature. You will have to weld up the old gas ports and drill new ones at the forward location. Be aware that the gas pressure drops off with increased l