Gerry, It appears to me that your radiator used to have those brackets/tabs on it. Probably when the radiator was recored/repaired at some time in the past, they were removed. I put your picture and my picture side by side on my screen. The radiators appear to very similar if not identical. Also noted is an area on your radiator fins/core that looks to have some damage to it. That is right where the bolt would hit the radiator if it was too long or put on without a washer. This confirms my belief that someone got careless at the radiator shop in the past.
The mechanics comments about it not doing a lot to help with cooling is probably somewhat accurate. However, I can tell you that putting my hand behind the Grille Star with the the engine running, with the shroud installed, did produce a stronger airflow then without the shroud. Not a lot more airflow, but an improvement.
My vote would be to remove the radiator and have some fashioned brackets soldered on before looking at an electric fan.
Many members report excellent results with an electric fan as a supplement to the stock cooling system. Just would not be my 1st choice unless there are no other options to solve your problem.
Keep us posted, and let us know how you proceed.
RB6667