Besides scrounging around for parts, this will probably work. Leave everything as is, "none", and just select the processor you want.
I would reccomend the clevo from the range above. Clevo build laptops that are kind of a barebones for all kinds of companies (rumoured to include alienware). The companies then modify them as they see fit and then rebadge them. Must be quite easy as companies like alienware completely change the whole look of the laptops as well as making them modular allowing you to upgrade "bits" of them