I finally got some time to continue w/this project.
MLT and BK are finished (almost, since I have to weld nipple for output valve and NPT/BSP adapter for RTD probe on MLT).
Since FB is made from keg top I used keg coupler and copper reducers with some copper elbows (thanks to KCBrewer for idea!), but I didn't soldered it to coupler for easier removal. It is working great and so far there are no stuck sparges.
There is 1/2" space from copper pipe and bottom of MLT, so deadspace holds only 0.5 cups.
I am still testing BK input pipe, I am thinking to raise it and position it horizontally for better heat exchange during cooling.