72"x30" will work, as long as you've got storage underneath, and perhaps something above, like a pegboard with those hang on plastic bins with the slash mouth.
I wouldn't run a case tumbler anywhere near my loading bench tough, run it on your regular old bench, it can be stored under the loading bench when not in use.
You also have to consider storage for your powder and primers too.
Check out this PDF.
http://accurateshooter.net/Blog/benchnrma.pdf