I want to upgrade my Internals.
For 360fps, you can basically drop a M100 spring in there and it's good enough, unless you want metal bushing(not really needed for 360fps but you want the comfort of just having metal bushing), shims if you are changing the bushing, upgrade the spring guide(bearing spring guide adds about 10fps), and a tightbore for accuracy.
Should I worry about an upgraded gearbox or anything?
For 360 fps, you shouldn't worry too much but it is a V2 gearbox, so the front is more fragile than the other versions of gearbox. Just don't use Aluminum piston, I would stay away from Aluminum pistonhead and cylinderhead as well, but that's just me.
Systema m100 spring or Guarder SP100 spring ( up to 370 fps)
What he needs is different than what he wants :)
the bearings in the systema FTK are garbage... 6mm bearing bushings FTL!
It's not that I want it, it's all I knew haha.