Is that a scout type scope? Mounted that far forward, it would need to be.
Sorry, it's not a scout scope. I'm not sure there are any scout (or pistol) scopes of that type, in that price range.
I have pistol scopes mounted on Eotech rails on my Mini-14's, and they do help at longer ranges - especially with my eyes. But, they are not as fast as a red dot at close range. They also lack the low light capabilities of a red dot.
If you do plan on ever taking advantage of the longer range capabilities on the .308, you might want to consider getting a red dot sight with a small dot (2 MOA), rather than one of the large (4 or 5 MOA) dots. At 300 yards a 5 MOA dot would cover a area of about 15 inches in diameter (20" at 400 yards, 25" at 500 yards, etc.).
The do make flip up magnifiers for the red dots, but all the ones I've seen are designed to use on AR's, and probably sit higher above the rail than you'd want on an M1A. They also sit between the red dot and your eye, and magnify the dot as well as the target.
The Vortex Strikefire has a screw in 2x magnifier, but comes with a 4 MOA dot.
If you can find one used (as they're no longer made) an Aimpoint CompML2 2X might be worth looking at. The 2x magnifier is part of the sealed unit, and is placed beyond the 2 MOA dot.