Hello Steve;
It looks good overall! It's a nice looking design bass, and you've obviously put a lot of thought into it.
A couple of suggestions from the engineering perspective:
Like 1n3 said, you need to do a perpendicular projection of the headstock, while you are there working in the computer. You want to be able to print that out and use it as an actual pattern. A full size print out, carbon paper and a pencil.
I would add a small volute on the back of the neck, right behind the nut. Just an 1/8" high smooth lump will make a big difference in the strength of that spot. Your scarf joint looks good, and will help the strength out on the headstock. But you could use a little more thickness at the joint.
Your neck/body joint is marginal in strength and stiffness. It isn't long enough, to my eye. It probably won't break apart, but it's going to be springy. That's going to affect your tone, making the bottom end mushy. I recommend that you extend the fingerboard maybe 1/4" back from where you have it shown, and bring the heel of the neck back to that same point. Move the two inner screws inboard 1/2". Make the neck pocket contact area longer.
Also, this bass design would benefit from adding brass heel bars, like I do on almost all of my basses. The folks around here call them BruceBars. They are brass (or aluminum) blocks set into the top of the neck before the fingerboard goes on. They have threaded holes to take 10-32 machine screws as the neck bolts. Much more clamping force between the body and neck than the conventional wood screws. Stiffening up the neck/body joint like this will significantly improve the deep low frequency range and the clarity of the deep lows. It doesn't make the bottom end louder; it makes it clearer and more defined.
I'm assuming that your body wood is going to be fairly soft, like mahogany? With a flame soft maple top? I'll recommend that you add a bridge block. An aluminum rectangular block, about 3/8" thick, that's set into the body right under the bridge. Set in flush with the top surface, in a bed of epoxy with a couple of wood screws down into the body. The top surface of the block is flat with tapped holes. Small machine screws bolting the bridge right to it. A bridge block will improve the high end clarity. It doesn't make the high end louder, just clearer and cleaner.
By eye, it looks like this bass might be a little neck heavy. Particularly if you go light on the body wood. You may have to add a little weight at the back end for balance. Or, extend the upper horn forward maybe 1/2"?
Other than that, it looks great. I think it's a good shape and structure and a good combination of pickups.
Carry on.
