ECsTwin, hit it on the head! Smith or Sadlak would be the way to go, if you are going to mount a scope on your M1A. Also, if you have Scout, you might want to rethink about putting an optic on there. The rail for the Scout doesn't dissipate heat very well, so your optic will start to get hot and the possibility of melting something is high! Obviously if you don't shoot round after round after round trying to unload your 20 round mag as fast as you can, then you're probably going to be safe mounting something on there. But I'd rather not take any chances.
Another option is (if you want a long eye relief type scope) is the Ultimak rail, this system will definitely be much better than the rail that the Scout comes with. Also gives you more rail-estate.
But if you do decide to mount an ACOG on your M1A, I'd get the Sadlak steel mount. The aluminum mounts are ok, but you are buying a tool, and you want this tool to last, so steel is the way to go!
For a cheek rest, I like these...
M1A M14 CHEEK PAD REST you can order specific sizes to match your needs.