Acid wash.  

Boric acid is what you want for residual roach killer. 

I guess depending on the numbers, you might want to have a cleanup crew come in to vacuum them up, maybe open certain areas, to vacuum.To kill them and eliminate them, go to a hardware store, or home depot has it cheap, get a container of boric acid.

Then we hosed it down and used some acid.

But it also gives leeway to the honest people to do what is needed to do the job right without throwing out the baby with the bath water.BTW, you do know that the "Chinese Drywall" problem encompasses several brands, and that the amount of sulfuric acid off-gassing varies not only by brand, but vintage.

I was going to hire a pro to acid wash it that way none of the detail is lost since this is sand stone from Scotland and I could give all the history and the cost of this place was crazy.

I'm trying not to use muriatic acid if I can avoid it.

Should I just treat the place with boric acid and traps for a bit before we start the rehab to be safe, or are german roaches persistent enough that you would recommend hiring a professional to come treat?  

lead (and other metals) typically enter the water from the water itself being to acidic and dissolving the lead from the existing plumbing, solder, and fixtures.  

I have used some industrial glass cleaner and tried vinegar for it's acidity, to no avail.