How properly to install the rack

[mekanik]

I found machinist who ask for 200 Euro for face milling on steel plates for mounting rails and rack. Its kinda too much. Any cheaper but good working solution ?

Just a note but i think you would be better having the rack the other way round (ie flat face to top) as you have it shown the gear and rack are going to get contaminated with all sorts of crap.
Perhaps you could fix the rack direct and adjust with spacers @ each fixing point, you could clock it in using a fixture on the support rails(gantry would be ideal)
Regards
Mike