Pay attention to the water pumps you're installing. I'm upgrading to the FlowKooler after doing some research as it gives better water flow through the engine through a better design. Also, an inline thermostat may not be a bad idea; since I installed my inline the Temps stays constant between 170 and 190 depending on the weather outside l.

 

Even though it's working okay now, I second installing an in-line thermostat.
I recently installed Extincts in-line thermostat. It's a good complete kit. My disco 2 temp only varies about 4 to 6 degrees now in normal driving, much better than with the stock set up. The in-line allows you to run whatever brand and temp thermostat you want, I installed a Stant 180 deg stat. I was concerned about warm up time and heat output since I live in the interior of Alaska. In the driving I have done since I installed the in-line, I found that the engine still comes up to temp quickly, and the heater output air is still quite warm, no change in those areas that I can tell. You'll not overheat an aluminum engine many times before it's ruined.