Try using something like the Modify FTK for the Aug.
That should give you everything necessary for upgrading. You've got a spring, spring guide, compression parts, bushings. Should be good to go.
Also it might be worth getting a new set of gears, maybe the Modify Modular Gearset (no shimming required!).
Finally, have you played with it yet? You should really do that first to see if it's good enough. Kind of like in programming, if you have a function that may be slightly inefficient why waste time making it more efficient when it gets completed in a reasonable amount of time so you can work on unit testing?
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE