I would dump the musician on the skeleton squad and split it and give the second unit a banner. Musicians on undead are not as needed as other armies. You would only benefit from swift reform, allowing you to move after a reform on a passed leadership test. If you tie a combat you and it comes to musician tie breakers you only lose one wound that is easily replaced next magic phase.
I would also looked into finding points for a corpse cart if possible, the always strikes first hitting your grave guard means you get str 6 hits at init 3, not a bad situation. Also, since its now a chariot you can hopefully get a flank charge to support one of your blocks and get impact hits to help soften them up before combat starts.
Ghouls I'm not sold on this edition, they got really expensive. Maybe its just because in abington we have alot of WoC players but T4 eats a lot of pain. At least skeletons can get a parry save and some armor, but in general are easier to raise and field in larger blocks. Don't get me wrong poison is great against the big monster that are stomping around but I dunno.
The wight kings are great BSB if you can find the points too, the screaming banner teams with an aura of dark majesty or fear incarnate means they test fear on 3d6 with -1 ld, or a re-roll of they succeed. Grave guard hitting on 2+ and wounding on 2+ is just fun to watch. Most people will dump on that unit though.