a good sized coolant system is the key. For an A sres a gemini radiator with a genuine nissan 75 degree thermostat is perfect.(along with electric fan)
water plus inhibitor with anti boil anti freeze is recommended in the ratio the manufacturers spec on the bottle. They can help keep temps under control..dont just use plain water.
The right radiator cap is the big key...the wrong ones wont seal or dont have the right pressure rating. A radiator system needs the right pressure to allow proper contact with the water jackets and keep air bubbles from developing.
Also they are so cheap but a new water pump..the old ones vanes corrode dramatically dropping flow and cooling.
With all this I could race my a series all day on a 40 degree day and keep temps atat 80 degrees.
On top of this any hot a series MUST run an oil cooler. Permacool do a good kit. Oil temps stayed at 90 degrees. The engine can be flogged all day iunders these conditions.