AC is expendable, there are lots of options in FA. Pick one that's available, I don't think AC is as dominating as the young OLs we have. Besides, AC is up there in age, he's using this negotiating tool of retirement as an excuse to get a better deal. Next man up!
Here is my Mock:
13: R1P13 Herbert, if we miss out, then Love, or Fromm
34: R2P2-DL Gallimore
44: R2P12 RB AJ Dillon
75: R3P11 EDGE TERRELL LEWIS
The above are my first four picks, the rest it's a crap shoot.