Some options:
The player I think that scores high on all our checkboxes for what we need is Harrison Barnes. He has great size and versatile skills on both ends of the floor and has been successful in that #3-4 role on a title team playing a similar system. I think he'd be a perfect fit with Kemba & the Jays. He is also considered a good locker room guy. But I don't know if SAC could be convinced to deal him. We would have to send out about 7M in salaries in order to stay under the tax.
I think Orlando has to be considered a prime trading target for this because they are so close to the tax. They have a bunch of RFAs (Fultz, Isaac, etc) that they will have to sign.
Fournier is a UFA and as things stand they likely can't afford to resign him if they want to resign those younger guys.
If they DO want to keep Fournier, then they need to shed either Aaron Gordon or Terrence Ross' salaries.
Net-net: They will probably want to deal at least one of those three guys.
Of the three, Gordon is my least favorite for what the Celtics need. I loved him coming out of the draft, but his shot just hasn't developed. I think it is critical that whomever the Cs get be a credible shooter. He is the best fit defensively of the three, but unless we had a 3PT shooting "stretch 5", I don't think he works.
Fournier is by far the most versatile and skilled offensively. He is basically a poor man's Gordon Hayward on offense. He has a good handle, a smart passer and can score from all three levels. He's an okay defender -- this is something he's actually improved at with age -- but not a great one. His size though, at least makes him a good fit in terms of switching in our scheme.
Ross is a fantastic 3PT shooter and would be a great space-maker for the Jays and Kemba. He's fairly athletic and gets up & down the court. Like Fournier, he's an okay defender, not a great one. He's smaller than Gordon & Fournier, though so isn't going to be great switched on bigger wings. He has an excellent contract. He's making 13.5M this year and it declines to 12.5M and 11.5M in the next two seasons.
Outside of SAC & ORL, another under-the-radar guy to look at might be Larry Nance, Jr., at CLE. He's an okay 3PT shooter, though not great. Very strong rebounder and very efficient scorer inside the paint. Good size to fit in the 'big wing' slot in our scheme and even potentially could do a little small-ball 5, though I think that would be situational.
Just some ideas. Very interested to see what Danny does.
To me, while it would be cool to get the perfect stud that fits, I think the marginal value of getting even 'just a good solid wing' is pretty high such that I think it could be a mistake in opportunity cost to wait for the perfect guy. Adding any of the above guys would be of immediate and dramatic help for our roster. If we end up waiting until next summer, trying to get 'the perfect deal' then we may miss out on getting a guy who could help with this coming playoffs.