6'8" is a big jump from 8'2". I might consider something a little more in the middle. 7'4" 0r something around there. Maybe just rent one that size and see if it works for ya. Doesn't look like a bad price though.
Get it and ride it. Cool thing is even though it's probably stolen (like a lot of the junk on CL) there are 200 just like it and it will be hard to ID. Ride her hard and put her up wet, you will learn a lot about your surfing. Win, win, win. Beware, deals to good to be true always are.