I am suddenly having a rise in my temperature gauge  that I haven't had before. Although the engine recently has been professionally rebuilt along with a new water pump could the thermal clutch fan need replacing? How would I check to see if is working properly?
  Walter 

What kid of temps are you seeing that have you concerned? A "fresh" engine can be expected to run a little warmer than "normal", until all of the new parts get "seated", or worn in.
The fan clutch should be nice and tight when hot, but a little loose when cold. It should not spin freely when you turn the engine(at operating temperature) off.
hth

For the longest time even after the engine was rebuilt the temp wouldn't rise more then 200 degrees which is not bad for a Big Block. The other day while attending a cruise the temp needle was pinned at 250. Although I had no visible signs of the engine overheating my concern was the clutch fan wasn't working properly due to the sound of the fan blade revving  while accelerating.

I don't know how old this clutch is but before I purchase a new one I thought I'd find out if that was causing the overheating problem.    Thanks, Walter

Is the heat rising more in traffic or cruising on the open road?  If you have an infrared thermometer you may want to verify that what the temp gauge in the car is telling you is the actual temperature.  Was the lower radiator hose changed during the rebuild?  If it was, does the lower hose have the "spring" inside of it to prevent collapse?

It was raising more in traffic ( stop & Go ). The hoses were all replaced at rebuild including the lower with spring. I don't have an inferred temp gauge but that's a good idea to try. When the engine is cold I can turn the blade ( by hand ) easily. It won't spin but it will turn with little effort.
 

Thanks, Walter

Walter that sounds right when it's cold but get it up to temp and see how it is then.

I'll do that tomorrow. Much appreciated!
Walter