Early in the season Stevens started Green at the 2 and wallace at the 3. The team obviously didnt have sucess but I think Green Green was fine as a SG.
If the Cs can upgrade their starting lineup by adding a SF who is more talented then AB then I'm fine with Green at the 2. He will not be a all nba performer on defense at the position but should be comparable to the other bigger SGs in the league. Converting Green to SG may be the best coarse of action if the Cs get lucky and end up with Parker in the draft. By drafting Parker and resigning AB the Cs would have a talented 3 man rotation at on the wing. AB would come off the bench (get about 26 mpg) at the 2 and Green ( about 32-35 mpg) could float between 2-3. Parker would start at the 3 and play some small ball 4 (32-35 mpg). Leaving Pressy or another pure PG with 12min per game that Rondo isn't on the court and Chris Johnson to fill the remaining few wing minutes.
With time this may actually be his best fit in the NBA. What many people don't realize with Green is that he is in fact a "small 6'9". What I mean by that is he measured in at 6'7.75" tall without shoes but only has a 8'7 standing reach. By comparison Bass measured 6'6.25" W/O shoes but has a 8'10.5" reach, Sully measured 6'7.75" w/o shoes and has a 6'9.5" reach. Lance Stephenson measured 6'4.5 but has the same 8'7" standing reach as Green. Dwyane Wade even has a 8'6' reach.
I like your basic idea but I disagree with your selective comparisons of measurements. At the small forward position, Green is by no means 'small'. Other than Kevin Durant (freakishly 6' 9" w/o shoes and a 7' 4.75" wingspan), there are actually very few SF's in the league who are much longer than Green (6' 7.75" w/o shoes, 7' 1.25" wingspan).
Carmelo is only 6' 6.25" w/o shoes, with a 7' wingspan.
Paul Pierce is 6' 6" w/o shoes.
Lebron is 6' 7.25" w/o shoes with a 7' 0.25" wingspan.
Paul George is 6' 7.75" w/o shoes with a 6' 11.25" wingspan.
I could go on with a more exhaustive list but those names should make the point. Green is by no means "small" for the SF position. I'm not sure why you are including Bass and Sully, who are not SFs in the comparison. All you are saying about Stephenson and Wade there is that they have freakishly long wingspans for SGs, not that Green is small or lacking length for an SF.
It's great that Stephenson has the same standing reach as Green. Green's max vertical was 5" higher though...
Returning to your basic idea though, I do like the idea that if we draft Parker or Wiggins that we put either of them in the wings with Rondo & Green, whether that means moving Green to the SG spot or leaving him at SF and playing Wiggins at SG (who I think would become an absolute nightmare for opposing SGs on both ends of the court).
You could also consider this if they draft Gordon.
Basically, if they draft any of Wiggins, Parker, Exum, Smart or Gordon, a case could be made for letting Avery walk. At a minimum, one of those picks lowers his negotiating leverage.