restriction of print jobs is possible using a script. We have various versions in place, whereby you can restrict jobs based upon the number of pages, size of job (Kb etc) and also jobs over a certain width.
I've attached the script we use to stop users printing jobs over x inches wide to large format devices. This is applied to the print job event. The principle for all the others is that same, you just look for and check different attributes of the print job instead.
Nic, my apologies for never thanking you for the script... Thanks!