A few random additions based on my (similar) experience:
I've used TSP & mopped the walls (ugh!). I feel it does a better job than anything else I've tried, but it's not available in all states. Do NOT buy stuff labeled "TSP replacement" or any such BS because it won't do the job.
Do not use water-based BIN or Kilz - not worth the time to put it on. Get the old-school oil- or shellac-based stuff & open the windows.
On that topic, nothing beats opening all the doors & windows & airing the place out for as long as possible. The drywall, studs, HVAC vents, subfloor & insulation all stink to high heaven, too - if I were able, I'd rip it all out & replace it.
Many people have had good results with ozone generators - I have no experience but it might be worth looking into as an adjunct to everything else. They can be rented.
Even after clean-up, you might well consider marketing it as a smoking unit as Nathan G. suggested, PROVIDED the fumes don't impact any other units through the venting, etc.
All I can say is "Good luck!" Been there, done that.