For what it's worth -- I had a parts truck ('52 3600) with a junk cab that I decided to remove the dash -- thinking it would make a cool wall decoration. So I went at it with torch and cut off wheel. I tried my best to save that dash but it, along with the cab, ended up as scrap metal.
After having tried to separate a dash from it's AD cab, I'm here to tell you that it's not worth the effort -- do as the guys suggest and go find a better cab. They're out there!
Good luck,
John