Greg, I always use Mason boxes. They are made in both deep and shallow. A true mason box has a lip across the top and bottom for securing the device. I mount them flush or out a little to allow for the stucco. If the stucco is to have styrofoam insulation behind it, then I fasten a handy box extension to it to make up the 1 to 1.5" difference.
Unfortunately, setting boxes in concrete/block/brick is a common thing where I live, I keep a box of Mason boxes on the truck, along with a box of rapid set mortar, and a box of 20 min drywall compound.
I am using ENT, I assume that is what you are talking about, since it will be cast in concrete at the top of the wall. We need tie beams here. I guess masonry boxes it is. I was just amazed that someone had not come up with a surface flange box deep enough to get the KO behind the block web. I sure couldn't find anything in the catalogs
I'm surprised that Arlington Industries hasn't come out with a solution for this yet. This is about the closest thing that I can think of that would address your type of installation, but it's a round box: http://www.aifittings.com/whnew102.htm
OK I am just going with the regular mason boxes and I will just pour these cells when they do the tie beam and dowelled cells. I am going to cut some plywood squares to hold the boxes straight while they get poured in.
Can you be there when the block masons are doing the wall. If so you can set the boxes where you want and let them cut them in as they go. You can even run your conduit along with them if they agree. If you don't have to many walls to cover this has always worked good for me. I use regular 1900 boxes with masking tape.
We are doing a delicate dance with the masons to get this done as easy as possible for them because they are doing me a favor. I would rather work when they are not here so I don't interrupt the flow of their work. I made up some plywood fixtures to hold the boxes with witness lines across the device mounting holes so I can chalk a vertical on the wall and get everything to be straight and level. I will saw cut holes, stuff the pre-piped boxes down the cores and attach them to the plywood via the device holes then tapcon the whole wood to the wall over the hole. When they pour the cells I should have boxes concreted in and sticking out 3/8" for the stucco. It took a while to make my plywood fixtures but it was more fun that watching 3 guys chip out 4 yards of concrete (the current step).