For what you have to work with I think you did very well,.

If you can, try to get the rear sights that were taken off, especially the original one made for that cut-out and have it reinstalled. That will look better than anything you can bubba up and may just be what is needed - economical mods were typical in the 50's and those old gunsmiths knew a thing or two about converting a combat sight to a target adjustable one pretty well. If it was a standard S&W rear, you might be able to find one to fit w/o too much trouble and then determine what height rear blade to use in it. Then you can adjust it to your ammo and have a nice gun for shooting.

Other than that I'd leave it alone but if you want to 'improve' it I would go the spray or home parkerizing route as cold blue is difficult to do evenly and never looks right. If recoil isn't bad you might replace the grips with some hand fitting wood. Then go from there.