I don't know any place that sells the neck that you want. However, you can buy a Carvin neck through and modify the end to suit your needs.
I built my fourth guitar with a deep set tenon and a bookmatched top and it turned out rather nice. The studs go into the deep set tenon and it has good sustain. Is it better than a regular tenon, bolt on or bolt in? My opinion is that it is just another way to do it. If you go with the Carvin neck through you can add wings and be done or add wings and plane the top so you can add a bookmatched top to it.
Good Luck,
Jeff