They don't have a kit listed online, but you can contact them to see if something for your application exists SSBC :: Brake Selector
Expect in the $1K range for the conversion. If you plan on getting a replacement vehicle in less than five years, don't bother. Keep the drums as they should be maintenance free for that period and not cost you a dime.
Most rear discs are NOT vented, due to clearance and the fact the rear brakes only do 35% of the braking. You can use the current hubs in almost all applications, unless you want over sized brakes.
Rear drums on the rear is a common place in most modern domestic vehicles which is starting to change (finally) for the 2009-2010 model years