I fought this for a couple years and here's what I found..
If your 4 row is brass it won't do as good a job as a 2/3 row fluidine/Be Cool or Griffin with the 1" or 1 1/4" tubes.
Ensure your water pump pulley isn't under-driven. March under-drives their crap and hurts our coolant challenged Cobras.
Make sure you run a "performance" T-STAT, such as Mr. Gasket (robertshaw made). They will flow more, under all conditions.
You can bypass the external water pump bypass for additional cooling as long as you modify the thermostat.
Ensure your puller fan is fully shrouded.
Ensure the inlet of your radiator is fully shrouded, all the way to the "mouth" at the front of the car. You WILL recirc hot air from the cooling fan's outlet if you don't at idle in traffic.
Flexalite drastically OVER-RATES their fans' CFM capabilities. "Professional grade" fans, such as Spal, tend to have true ratings.
Ensure your timing and fuel mixtures are correct. Lean conditions and incorrect timing can aggravate coolant temps.
***most important!! Make sure your electrical system is up to the task of hi-amp draw fans. Alternators/wiring and rugulators (read: Painless wiring harnesses) are NOT usually up to the task with under-sized conductors. With the usual accessories running at idle, check your voltage to and at the fan. Mine was 10.2 volts before I straightened things out!
Dave