Actually it was the early 603s with the head issues, not the later ones (350s heads were actually the best, it was the bottom end that gave out)
Trust me I know all about that.....(I have a 87 300D engine in my 350
)
Thankfully my donor car had the updated head already installed on it so I really don't have to worry about it anywhere near as much as the old #14 castings (Although I know of at least one person who has +500,000 miles on a 14)
I believe that I still have the 350 head, injection pump, and turbo.