First, that stock seems WAY too expensive.
Why not go with a RRA M4 stock? Bravocompanyusa.com has them for $65.99 with buffer and spring.
Seoncond, if you are going with a two stage trigger and a samco grip, then you may want to just buy the other lower parts separately. If you buy the LPK you are going to be paying for parts you don't use. If you aren't sure exactly what you need, then reply and I am sure one of us can post a itemized list of the small parts.
Since you don't have a barrel listed, I am guessing that you are looking for a complete upper assembly. If you don't have any tactical purpose in mind, then I would go with a 20" heavy barrel with a flattop receiver. If you are wanting to work on pure marksmanship, then you can't go wrong with a standard carrying handle with the A2 sight. The peep will force you to use the fundamentals. The flat top will allow you to add optics later if you want to work with them.
If you want something a bit lighter to carry, then I suggest a standard 20" Gov't profile, or even a 16". I have a Bushmaster 20" heavy barrel on my precision rifle, and I don't think I would like to have to stand a post with it.