If it's a genuine SAI jump on it. If it has any wear problems SAI well fix it for free. All the M1A's have a life time warranty that follows the rifle not just the original owner.
There was a bolt recall on early rifles, call SAI with the serial number and they take care of it.
Bolt rollers can be a problem, keep the roller well greased.
SAI extractors are not the most robust part, replace with usgi part.
Lot of gi stocks floating around for these, both wood and glass.
M1A info here.
I would say take a look at the wear on the parts. Little wear means little risk. All GI parts are an absolute bonus, though you would only be able to tell that the bolt, operating rod, trigger group are GI because they are stamped.
Got to be careful with looking at drawing numbers for usgi identification. SAI marks there commercial parts with drawing numbers very similar with usgi. These well have "SA" in the drawing number, if your not familiar with gi drawing numbers it's easy to mistake them for real usgi.