GSG,
You don't mention the driving conditions when you are experiencing, what you consider too hot for your expectations.
If your radiator and system are clean and has recently been re-cored, then that's not your probable issue.
Just for curiosity, are you still running the Z-S CD150's or a different carburetor setup? Is the ignition original or an electronic aftermarket set?
If your car has no issue of overheating driving at speed on the open road, but only in stop and go traffic around town, the most likely cause is a lack of cooling airflow at low speeds. The same issue as Tigers and most of the same fixes are applicable to Alpines as well.
Some definitive testing on cooling airflow posted at the TEAE website:
www.teae.org
As Michael stated if you are still using the original gauges, do you know if the the temp gauge is reading correctly? If the "gauge voltage stabilizer" is missing or the internal contacts are stuck closed, then the temp gauge will read higher than it should indicate.
There is a small probability that an engine tuning issue could be at work. Retarded timing and lean fuel conditions can lead to higher operating temps.
Lastly, Michael's question about if the block has been flushed is pertinent but may not be enough to solve the issue. 1725 engines have a known issue of having "gunk" deposit in the rear of the block around the number four cylinder which restricts coolant flow. At one time, there were some water pumps which had not been assembled with correct impeller to housing clearances giving reduced coolant flow to the engine.
The Rootes engine overheating issue that is often discussed, sediment build-up in the water jacket around cylinder number four. This montage was just posted to YT a few hours ago. Thanks to Arrow 5 and his shop for the video.
forum.sunbeamalpine.org
Please supply more data and someone will probably help with a more specific answer.
Hope this helps,