Hi, during my cement block home build my contractor (long gone) installed these boxes 

Now after finish work and wiring was done, (by third world nice but inept workers),  most need to be extended, some up to 1 3/4″.
Can anyone come up with something that will work? There are no Building codes here…, but I want my switchplates and outlets to be stable and flush to the differing depth plaster walls. The wiring was just completed after a month of tracing wires. (First electrician past away without notes, by a friend of original guy who regretfully was the nice but inept guy)!

I’m at wit’s end with this 10 year build ..