With many thanks to Cimarron I now have an adjustable rear sight on my .45 Cal 24/7 Pro. He started with a Browning HP TPU sight from Precision Sales International and modified the dovetail to fit the pistol. Installed easily and seems to fill the bill. I will need to open up the notch a little to allow some daylight in between the sides of the front sight and the rear sight to get a better sight picture.
Here are Pics.