They're take of points for brake vacuum, for what they're worth. The other smaller vacuum points are in the TB's themselves.
This all brings up an interesting discussion. I have mine setup with the fuel mapped via TPS position and the ignition mapped via manifold vacuum. That works well for me, mainly because I don't worry about cruise conditions, where accurate engine load is needed for ignition timing. You could just set yours up with the ignition mapped via TPS as well. If you have the table load points setup correctly, this works perfectly well. Let me know if you need guidance.
This all brings up an interesting discussion. I have mine setup with the fuel mapped via TPS position and the ignition mapped via manifold vacuum. That works well for me, mainly because I don't worry about cruise conditions, where accurate engine load is needed for ignition timing. You could just set yours up with the ignition mapped via TPS as well. If you have the table load points setup correctly, this works perfectly well. Let me know if you need guidance.