The frame is teh heart of any build.
If your heart is set on a zaskar why not just wait and get teh frame you know you want. OK so a zaskar frame is going to be £65-£125 depending on condition,year,etc.
You could end up building a timberline with quality parts then later on having to transfer then onto a zaskar.Then dispose of the timberline frame
I'd only build the timberline with cheap/free parts as use it as a pub bike/leaving at the station bike.