Do some more shooting before you scope it. The M1A has the best irons made. You can get different size apertures and different size/style front blades. The "loaded" model should have SAI's version of NM sights, they can be improved upon. I find I shoot my iron sight M1A about four to one over the scoped one. Tune the blade and aperture to your eye sight and blast away.
Check out the Sadlak mounts before you buy anything.