Im thinking of fitting an electric water pump to a rover k series engine to aid circulation but mainly to stop heat spots in the head when it is switched off
what are the pros and cons

Won't make any difference just ensure you have a proper by-pass hose connection --- ideally using a PRT thermostat.
The K series head is very stiff main issues concern the liners sinking into the block and the plastic inlet manifold leaking at the outer corners.

I am rebuilding an engine at the moment and have opened up the water ways in the head as the casting flanges were still present also I have drilled and tapped the back of the head to fit a temp gauge that will be wired to the water pump so as to stop heat soak when turned off after a good run
Yes I have a PRT from a freelander to fit
What do you call a proper by-pass connection ? please
Mark

I dont really understand why britishtrident says it wont make any difference? Ive used EWPs on bike engine kit cars and also supercharged car engines to do exactly what the OP wanted? The extra heat the engine produces on track days and hard runs is a big issue. I use a Davis craig electric water pump with digital controller. It can be set to whatever temp you want and will also turn off at your desired temp even after the car is turned off.

It has helped me massively with engine cooling and reducing hot spots.

Personally I think it's a good idea and will stop the engine overheating if it becomes heat soaked and has no downsides. I'd also make sure the fan is live during that time in case it needs it. Are you going to use a timer or a thermostat to control it?

The only thing I'd maybe do is run it (pump & fan) through a low voltage protector so if the switch did become stuck on it would not drain your battery to death, but might be overkill... till that day it does