Hi Bryan, so this is going to be a 4 string bass ? Might pay to build a bass kit before attempting a scratch build. Or think about ordering a bass neck. There is alot to learn about building a scratch neck and some specialised tools are required.
Also a bass truss rod will be longer and more rigid than a guitar truss rod.
Will the neck be fretted or a fretless ?
You will need to route the neck pocket to suit the neck heel profile/shape