Planned Non Op for Engine Drop -- Smog?
 

I would someday like to drop the engine of my 83 SC to plug leaks, change oil return tubes, adjust valves, upgrade tensioners, etc.

I know that once I drop it, it will be a long time before I finish and put it back in. So let's say that the engine stays out for more than 2 years, and that I do a Non Operate thing with the CA DMV. Will the vehicle be exempt from smog checks?

You are correct... during the non-op, No smog is required. When you're ready to take it off non-op, you'll need to smog it.