The first thing I would do is take her out and shoot it. See what the rifle is capable of as is, and go from there. Springfield Armory uses 2 types of std contour barrels for thier rifles. USGI chrome lined 1-12 twist, and non chrome lined (Wilson) 1-11 twist bbls. Try out a few different loads, and see what she can do. If more accuracy is reqired from this point, then I would recomend that you contact a qualified smith that you trust, and go from there. Just my .02 here, but if I was going to build an M1A up into a NM, then I would want to contact the builder, and find out how much the build would cost, prior to buying any parts for such a build. ( Feel free to PM me in regards to info about the smiths I have had build me a decent shooting M1A/M14)
The name of the game with this type of rifle is to achieve consistant and smooth movement from the moving parts of the rifle as it is being fired, regardless of the type of barrel used. IE.... the barrel in and of itself is only part of the equation.
Here is my example........
This rifle started out in life as a Norinco M14 with all OEM parts that I picked up yrs ago used for $350.00. I took it to my smith, and had him check the specs of the reciever to find out what we had to work with from the get-go, prior to anything else from that point. Since my intent was to use a USGI bolt and trigger group for this build, I wanted to insure that the reciever was to spec. (IMHO, the chi-com M14's make a decent forged reciever for a build)
After that, I told him what kinda build I was lookin into. In this rifle's case, I was lookin for extreme reliability in adverse conditions, decent accuracy with a wide range of loads, from milsurp (147gr to 155gr), and commercial loads (110gr up to 175gr), and hunting loads (125gr to 168gr), and to keep her as light and compact as possible ( USGI synthetic stock without any bedding, such as glass bedding the action). Since your lookin to build somthin more along the lines of a NM rifle, a heavy barrel such as Krieger, and glass bedding may be more important, and you most likely will be better served by narrowing your field of loads to somthing along the lines of 168gr FED Matchking, or similar loadings.
So........with a decent reciever to start with, and my intent for this paticular build understood, we went from there............
1. Criterion 18.5 in chrome lined std contour 7.62mm chambered 1-12 twist barrel, and a NIW USGI (TRW) bolt
2. NM trigger job using a USGI (OM) complete trigger group.
3. Unitized gas system donr up by someone that I trust, and has a good rep for this kinda work. Piston is a tin coated Sadlak.
4. Sadlak NM op-rod spring guide. New USGI op-rod spring.
5. Smith Enterprize Vortex direct connect flash hider, and gas lock "hooded" front sight. (Note: This eliminated the need to have a std flash hider reamed out to NM specs, eliminated the whole castle nut feature/parts altogether, and since this build's primary intent is to use optics, the shorter sight radius of the GLFS as compared to the std front sight system was less of an issue. Your build might be better served with the std type system, especially if you plan to use a 22in heavy bbl.
6. Norinco op-rod. ( Upon examination of the org op-rod, my smith advised me that there was no real need to swap it out with a USGI, and since the price of a decent USGI op-rod is rather high, I took his advise.
7. Norinco rear sight assembly. Same as above. It met specs, and works just fine, so I opted not to replace it. Your build would most likely be better served with a NM rear sight assembly, unless you plan to use optics.
8. USGI synthetic stock with very tight lock up to the action. I filled in the selector lever hole to keep out unwated nasties from gettin to the trigger group, and strengthened the forend to prevent flex when I 'sling up".
9. Last but certanly not least.......... this build was put together by a smith who specilizes with this type of platform. BTW.....since your rifle is a Springfield, you might call them and see what they would charge to build her up into a NM.
Total cost came out to $ 1227.00 give or take change to include the org rifle purchase.. If I was starting from scratch today, this figure would be a little higher most likely.
Round count hit the 8000 mark last weekend with 0 issues.
Accuracy across the spectrum of loads that I put thru it keep inside a 1in circle at 100yds for the most part, with her favorite load inside a 3/4 in circle consistently. (off a bench using optics)
10 TX hogs harvested to date, and will use it for deer hunting to boot.
Hope this helps some.