So, there's all of my ideas:
1. Make SCP-173 only as the Red Monster (looks better than 2 monsters in one being, because Red Monster have the same behaviour as 173).
2. Use the old model of SCP-106 (from 0.1-0.5.5, with its source code) and retexture it to the Masked Man (or use the original "mental" model).
3. Retexture SCP-096 as Rake and SCP-035 as Masky (watch my previous post).
4. Make a new texture for SCP-860-2 (like Smile.dog itself).
5.
(Unnecessary) Use the new model of Slenderman (I can send it for you).
Also, some new textures for SCP-860 and Intro Door (used from Slender's Woods):