If I'm the Cavs, a large majority of my targets are 6'5"-6'9" and under the age of 30.
Harkless and Terrence Jones would top the list, but both are restricted.
Solomon Hill, Jordan Hamilton, Quincy Acy, and Cleanthony Early are other guys I'd look at. Bigger wings that are still young enough to grow as players. Maybe we catch lightning in a bottle and one of those guys prospers in a good situation. It worked for the Spurs and Danny Green.
We need to get some younger guys in here instead of relying on the old folks home every off-season. If Richard Jefferson comes back, how sure are we he won't be washed? He's definitely shown glimpses over the last few years.
In terms of bigs, I'd look at Miles Plumlee, Meyers Leonard, and Dwayne Dedmon even though the first two are restricted. Can't hurt to make an offer.