Against melee you'd be better of playing with aphyxiate over chilblains. Stun, half stun, hex ... But even to counter openers vs say a hunter/feral team, it has a 30y range, which is absolutely sick.
Conversion is really the talent to go. I often do 1v2 as unholy to cap alts I don't actively play, and you don't die that easy. Combined with blood presence (you will no longer get those free death coils in blood presence though) that means a lot of survivability.
As unholy I prefer blood tap over runic corruption. You can get 6 necrotic strikes per dk this way.
Gorefiend's grasp: desecrated ground is a free extra trinket for your dk's, though I can definitely see why a boxer would want GG.
Purgatory might have some use as a boxer, but lichborne is so good, you can macro it so that it becomes an extra heal. It obviously breaks fears as well (and sleep effects from the warlock pet).
As a resto shaman I'd try out totemic projection with this team, definitely if you give up chilblains for asphyxiate: you can relocate earthbind totem to assist your dk's. Not to mention that relocating capacitor totem influences the positioning of the enemy team (landing it is ofc nice, but just making the opposite healer move out of his comfortable position can create opportunities as well).

If you don't want to give up chilblains you could always go for 1 chilblains and 1 asphyxiate. Same with gorefiends grasp. But asphyxiate will both increase your shamans survivability and your offensive pressure.

Unholy dk is all about sick pressure through landing necrotic strikes while your diseases are ticking. As a boxer it can be harder to manage your runes properly compared to braindead frost, but if you get outbreak going, 2x festering strikes, build up 10x blood tap through death coils, and then manage to land 6x necrotic strikes x2, pop your pet+unholy frenzy + trinket/racial ... any target will die.

Frost might be easier, but unholy is so much more rewarding. And works better at higher ratings. Really if you can get the hang of this team, you can get really far.