Why not use a program like faceGen to create completely new faces?
you mean new textures or new models?
Felix's and Miguel's head for this project were done in facegen.
Brex's, for example, was ported right off a HL2 model.
Kiska's was also ported but I had to edit it manually to fit BC. same with Saffi's (but this one looks like a woman, at least.)
EDIT: early pic of Miguel re-facing. and that's all for today.