Not sure I see them going after Kemp. But for conversation sake let's say they did,
Kemp (14:$21M, 15:$21M, 16-19:$21.5M annually or 6/128M) for Dempster( 1/13.25M)+Gomes(1/5M) as the base of the deal. LAD takes on both Sox players contracts plus 30M of Kemp. Sox get Kemp for 6/98M. LAD Takes on 48M a Mid rotation SP on a short deal, 4th OF on short deal and most likely a SP prospect.
Yes obviously the could just sign Ells for around that(maybe) but Kemp isn't only replacing Ells, he would be replacing some RHH power in the line up. I could see them moving him to LF as well and going with JBJ in CF with Nava being the fall back option.