A Word About Safety
It's worth stressing at this point that we're fully committed to anything that makes flying safer - as our safety record demonstrates. The EU-OPS legislation is well-intentioned, but it lays down requirements that are impossible or impractical for vintage aircraft.
Fitting oxygen masks to an aircraft that never flies high enough to use them, or equipping it with chutes to deliver passengers to the ground four feet below the exit door would be prohibitively expensive - even if the items were available. And these are just an example.
Sadly, from July 15th, we have to withdraw the Daks from passenger flying
This is from
http://www.airatlantique.co.uk/ it doesn't tell you much about all the changes needed but as said before the cockpit would have to be locked etc.