Steve,
I don't think there's a need to change the
oil after one event.
The fan sounds fine. Definteliy upgrade to a Griffin or Howe aluminum radiator, they really dissipate the heat much quicker.
YES...the Water Wetter DOES work! Good for 10 to 20 degress in some cases, but slapping the car will still keep the temps up. Keep a mix of 33% anti freeze to water in the radiator.
You defintely need to add an override switch for your fan. That way you can turn it on when you want. By the time the 'stat activates it, its already climbing. I warm my car up a few laps, once the temp is up to 180, I turn on the fan manually.
Most small blocks are border line for their need for an
oil cooler. An
oil temp guage is a MUST. Then take it from there to see if when you run the oil gets hot.
A road race oil pan and/or Accusump pre oiler are preferred as well when racing. It gets expensive, but these upgrades will help protect your engine from failures.
In regards to your 3 link...stay in touch with Terry Shank (RW+B #16 FFR from Pocono), he is just starting to use his 3 link and will gain a lot of knowledge on the setup from the Glen event.