Depends on the new engine, and if the mod is still actively maintained. It seems that WCS has a number of coders, but maybe not one central person to organize it all. ZombieMod saw a release last year, and the main developer for it appears to be posting on their foum every once in a while. I'd bank on ZM being updated before WCS, but I'm not intimately familiar with either project.
Manimod is updated for use with TF2, which uses the orange box engine, so it should be easily adaptable to the new CS:S beta.
Kiro : us fireyes got dumb by his girl that y he is suck