Xack 98% of the time all new motors run hot for 5-10 heat cycles before running at a cooler level. The first thing I will ask you is what size pulleys are on the motor? If the crank is underdriven this will start a problem. Next is air flow in and out of the motor compartment. Does your coolant fan have a schroud on it? If you are running the car in the driveway, do you have a fan infront of the car to help cool the radiator? If your radiator is standing straight up and down in the car you are getting max air flow. If yours is at an angle, you may need a splitter in the nose to redirect the air into the top of the radiator like an ERA car. Do you have the small dual fans in front of the radiator? If yes, they also cause a loss of air flow to the radiator, they do look cool when running. Open the hood if running the car and not moving. Back to the waterpump, they sell a plate kit for about 10-15 bucks to help in crease water flow in the motor. It rivets to the impellor of the pump. If you can remove the rearend plate, yo can see this. Becareful to not damage the gasket or you may have to make a new gasket from scratch. This plate will increase the flow 10-20 %. As far as the AUX water pumps, they are more for 1/4 race cars to help cool the motor between rounds. The other thing is you should n't run a thermostat with these pumps. Once the motor thermostat closes there is very little flow. We run flat plates with a hole or holes in the plate for the coolant to go through. If you have a long coolant run between the motor and the raditor, you might use this as a helper pump. Problem is how long the pump lasts and if it goes bad, what do you do to fix it on the side of the road. It's the same thing as electric water pumps for motors, some guys get 2-3 years out of them, some get only 1 season. Alot of money for very little gain in help. I think you will find that it is more important to get the best hiflow coolant fan with schroud, high flow thermostat, and stock size pulleys for the motor. If the charging system is not putting out enough amps at idle with the motor running and other electrical curcuits on you will kill the battery. This is a whole other thread. Last note, if you have a long run of radiator hose and it doesn't have hard wire inside it to stop it from colapsing you may want to change this to exhaust pipe as must as possible. Also double clamp all radiator hoses with clamps 180 degrees apart. Good luck. Ps it is also possible that you may still have air in the system and need to either jackup the cars front end to force the air to the front of the motor and out of the coolant system or have the system vacuumed down to fix the same thing. If jacking up, WATCH the
oil pressure and have an extra quart in the pan. This will not hurt anything.