How do you comply with NEC receptacle requirements in row homes with brick walls?

I'm rewiring a Philadelphia row home, which like many others, has brick and cinder block for the side walls. There is no framing, just lath and plaster. I know some flippers will put in 2×3 studs to make things easier, but I'd prefer to avoid this for reasons of both cost and space.

What they Originally did was chisel away part of a brick and install the receptacles in the base trim. At the time they made small, narrow boxes, probably only 1 1/4" deep and completely flat on the front with wings made to nail into the trim. I have looked all over for these. I can't even find a picture of one. How are people handling this in renovations? The only other solution I can think of is that ugly plastic channeling that runs on the outside of the wall.