choosing a co-driver/navigator for future SORC events ???

Open road racing is pretty much on the job training.  Get there a few days early and practice the course multiple times.  Take advantage of the "rookie" programs that many ORR's have that give tips for drivers/navigators.  The BBORR has a rookie event a few days before the race where you can run a 10 mile section of road at speed.  Enter a slower speed class the first year, video it and watch the video over and over to learn the course. 

When we started we had notes for every turn for every race. Then you put times for these notes and try be at each point at a certain time... but this method discourages "banking" time and banking time is the key to moving to faster speed classes and you throw most of these notes away.

If we are running the BBORR 140 mph class, we run 150 mph average where we can (banking up to 50 seconds) and 130 mph average where turns are tighter and the course is slower (using the banked time).  You only HAVE to be exactly on your time at the finish line of the last leg.  

It's good to have a driver or navigator who has run the race before as a Navigator for your first race to help with your learning curve, but going to a race and asking the drivers/navigators how they do things is the only way to learn the tricks.

Motorcycle helmet coms work good for driver navigator communication. You want a navigator that doesn't get car sick #1.