I have a couple builds in mind....but probably a standard Jazz bass. Like a fender but with better quality parts.
also considering a 54 p bass...
Good choices. Passive basses are a simpler build with minimal woodwork. As stated above, watch the depth of your pilot holes. Also, if you intend to have a pickguard, order the 20 fret neck. They don't cut truss rod notches for their pickguards, you'll have to notch them yourself and it's much easier to adjust the rod without that overhang from the 21 fret board. Otherwise you'll have to remove the pickguard when you need to make a relief adjustment.