Buzz
You might want to ask guys over on the "3RS" forum about the Kadee conversions. I'm sure someone over there has done these cars by now.
From your photos, it looks like the cars are pre-drilled for the draft gear boxes as is usual for Atlas equipment. You probably just need some styrene shims and Kadees with the correct shank length.
That's a nice layout you've got started there. Good luck!