Dave,
Here is my 2 cents. I love Kadees, but I would put in a plug for the smaller #1 size (820, 821) or the rust collered variety (920, 921). From your previous posts, you seem to have 1/29 equipment and I like the look of the smaller coupler. I also echo the above remarks on body mounting--though that depends on your minimum radius curves, though yours look pretty borad on the postings of your new S.O.B. layout.
Here are some photos of my conversions, and a photo of the most important thing you need; the 829 (#1) or 880 (G) height guage!!!!!
My aristo covered hopper, just the box is mounted the coupler still need to be painted. This is an 820 on a piece of PVC. I tent to drill and tap for screws, rather than glue my boxes on. And with those coal drags you are running, that might be a great idea.
These also might help. Cut the tongue off the aristo truck (this one is primed waiting for paint):
This is an LGB tank car with the short 821:
And my most involved conversion--a custom coupler pocket for an 820 on my Aristo Evans box car--this is supposed to look like the prototype cushon unerframe, they really do stick out from the body like this:
As you will also notice, I cut off the trip pins. I don't use them and I will place "air hoses" on my equipment. This is a purely cosmetic choice. I use a razor saw now, careful with a dremel--the trip pins can get hot enough to melt the coupler enough so it does not work--you can guess how I figured that one out!
Hope this helps.
Matt
i have a 50/50 mix and they work well, some had said they had minor clearance issues with 830's on 10ft dia, but i have not had any problems with them... 
