If i buy a trijicon reflex an A.R.M.S. throw lever mount and a swan sleave will the dot apear lignd up with the front sight post as it does with an aimpoint.

A Swan Sleeve will raise the Reflex up but I will get it too high to use any kind of BUIS. Get the arms mount with the necesary spacers to get the dot up as high as you want it.

IPSC_GUY sends

If you intend on using a swan sleeve: the ARMS#15 is the mount for this, the RX15 from Trijicon might be ok.
If you want to mount it to a flat top: the RX14 is the proper mount.
Because the Reflex attaches to the mount using 3 screws I don't think there is a spacer system on the market.

Basically the RX14 raises the sight for cowitness using a flat top and the ARMS#15 for use on a sleeve (such as ARMS#38 and SIR)