I decided I wanted to run the hand held circular saw on a track to keep the cut nice and straight. So I made a track and screwed it to the frame.
Then I cut the notch out by running the saw back and forth on the track but shifting the saw away from the fence an eight of ah inch or so each time. The stupid saw tilted a little bit to the right when I was hanging it over the edge of the track a little bit. Partly my fault, but it's also a cheap saw that doesn't have the flattest base. So you can see on the picture below that the notch is perfectly flat on the edge where the saw was against the fence, but a little bit sloppy in the depth. I may have to fix this by cutting deeper until it really is flat, and then gluing a block in there to get it back up to the correct depth. You can see that I also drove a bolt into the frame that will hold the bracket that clamps the blade guide arm in place.
So I put that bracket on and tightened the knob I bought to see how well the arm would clamp in place. Even with the sloppy cut I mentioned before, it is rock solid and aligned extremely well. Woot!
The blade guide slides up and down beautifully and clamps rock solid in perfect alignment with the blade. I'm loving this!