I am following this thread with interest. My M1-A is currently iron sights. When I bought it, it came with a Springfield Armory scope. I can't remember the magnification off the top of my head. I recall a lot of people bought the rifle with that "free scope" deal and made a good chunk of change selling the scope. I used that scope with the rifle during a long range rifle class I guess ten or so years ago now, and the combo performed well.
Now that I have AR rifles and an AR pistol for that 50 meterish home defense range, I'm kinda thinking I want to set the M1-A back up with a scope for longer range. I'll grab the scope out of the reloading room later and post what it is. It might be good for what I want, or maybe I'll see a better recommendation here.
I still say the Garand and M14 style iron sights are some of the best around. Even my aging eyes can still acquire them well.