I would make sure the Aimpoint will co-witness on the #39 (if you are wanting this).
I have an ARMS #39, the C-More, OKO and ATN UltraSights will not co-witness on the #39, I tried.
I would suggest testing it first or buy the scout mount for the Aimpoint. Let me know, the Aimpoint is what I was going to try next.
~s0ulzer0