Hello Stempies - another 'nice to see you over here' from me as well !
Like you , I have an early 280SE , mine is an 84 on a B plate , but like yours has air con ! It seems strange , but I know of a couple of other people over on the MBOC forum who have 280SE's with air con , yet lots of newer and larger engined variants don't !
Mine is not quite so original as I've been fitting a leather interior plus a few other options not originally on it - but I'm only fitting genuine MB parts from other cars I've found breaking so at least it looks authentic .
Your car looks lovely , pity about the door damage but at worst there are plenty of cars breaking if you need a door .
Take good care of it .