Thanks Octopus. Those were just the tips I needed. I really appreciate the thoughtful response.
I got some free time yesterday and finished off the project:
Bourbon box with on/off switches and speed control knobs.
Box from the top showing plastic sliding top and hardware inside. Notice the notch with the power cord. For storage I can slide out the top, coil up the power cord, and store the adapter right in the box (my old homemade stir plates had the power run through a hole in the side of the container which meant the power adapter was swinging free and getting tangled up with everything when not in use).
The guts of the system. I found a 2.2amp output adapter. As directed above, I simple connected all the black power wires and all the red return(??) wires and otherwise setup the system as in the instructions from my first post.
With the 2.2amp adapter, I get enough speed that I get a good dimple at the surface when both are turned on.
Thanks again for the kick in the right direction on this project!