On the banless FAR legacy rifle?

I just called them today and they said they could sell me one with a flash hider and bayo lug for the same price.

I've always wanted an SP1ish gun.

Yes. Better yet, get an Ashley same plane aperture.

The A-2 is a bit wider but will fit. Since it is wider, windage is lost, to some degree. If your barrel - fsb., is on good and square, no sweat. If not, depends how far off it is. In otherwords, if you need too much windage adj. to zero, You will have less than with the A-1. Does the rifle zero with the A-1/ That needs to be seen first.
The ashley [A.O.]  I got was for s#&t. Same planet sight mabie. In my humble experiance. A-1, A-2 , which ever one you want will interchange.

The A2 aperture will fit, and while you are at it, let me suggest two more improvements to really take advantage of this.  (I did this on my A-1 uppers)

(1) Replace the rear A-1 aperture with A-2.

(2) Replace the windage drum with the "Rapidex Windage Knob", which requires no tools to adjust, and has 1/2 moa clicks.

(3) Replace the A-1 round front sight post with the A-2 square front sight post, for a sharper image.

Zero with the small aperture at 50 yds.  

Flip to the large hole and hold dead on for 0-250 yd shots.  Flip to the small hole for 300 yds.

Call in air support for greater than 300 yds.

Seriously, this works well.