"Gun store guys"... the BANE of the firearms community since 1866...
If not a riser, than a gas block front sight (they're made taller), and make sure your front sight is METAL. Magpuls ARE nice and good kit... but have been KNOWN to react 'poorly' to blazing hot gas block mountings...ah well got a riser coming, and... an ambi safety, ambi bolt latch, extended length carbine quad rail. Also got 4 30rnd dark earth PMAGs for $20!
Ambi-stuff is convenient on a pistol - on a rifle, it can easily cross you up, though. Are you a lefty? IF not, I'd probably hold off on some of that, and save for a DECENT optic. By decent, that would be - Aimpoint, EOTech, or Trijicon - especially as CQB optics.