Well my power decided to go out when I was almost finished with my post the first time, so for the second time...
I don't use GW paints but heres what I would do..
#1 THIN YOUR PAINTS (I'm sure you already know this but it doesn't hurt to be super duper sure.)
(darker) Bestigor flesh
(lighter) Ungor Flesh
This covers all of the XV-88
(darker) Bestigor flesh ---> Screaming Skull
(lighter) Ungor Flesh ---> Pallid Wych flesh
these layers are applied thinly and numerously slowly working your way up to the high parts and leaving the lower parts darker.
(darker) ----> high lite in bone
(lighter) ----> high lite in white
use that earth shade wash in the cracks. I generally suggest using an oil wash so that you can coat the whole thing and then wash the faces off with a q-tip afterwards so it doesnt darken it. Because that earthshade will darken the whole thing. Or you can go over in a gloss and earthshade it so the wash runs to the cracks and then matte over that.
Basecoat: Screamer pink is the only pink one they have so I guess use that.
(personally I would use emperors children, its the best pink IMO)
Then you just use thin layers of rakarth flesh over that to bring it up. high lite it in white and do a really really really thin wash of the emperors children after that. or even a light earthshade.
Ive used the duruchi violet and I don't think its the color you are looking for its too dark. I would go the pink approach.
Or there is this: https://www.youtube.com/watch?v=5_waL7TUwFo
I dont know your paint style. I tend to build up, this guy uses lots of washes and high lites. His skin is more earthy I prefer the pink/purple look.