The only danger in setting too high a goal here is that it may lead to overtraining, as a misuse of enthusiasm. If he is unable to reach 8x6 he will just quit, as most of the people do.
Guys, it’s quite possible for him to reach the goal. All it requires is years (a lot of time) and intelligent work. The reason most people here don’t reach their goals is because they do things that don’t work (they don’t analyze their results or methods and reasons preventing further growth well enough and instead just continue doing the same old thing) and quit too early.
With hanging from different angles, with and without fulcrums, and a good vacuum ADS plus a few years, most length goals can be achieved. With enough focused expansion of the tunica and a few years, girth gains can also be achieved.
All that it requires is an intelligent, investigative mind, no stubbornness, and dedication/time, I think.
Set your goals high, but work intelligently. Consider why you are doing whatever it is you are doing (example: I am doing RSDT SO hanging because the septum is the limiting factor in length gains), focus on a divide and conquer approach, read as much as possible in the actual PE forums here (not off-topic ones), be consistent, and be patient. At some point you may discover future gains are not worth the time, and you will quit, as most others do. Otherwise, you can probably reach your goal.