you're quite limited in your choice if you're after the standard 205/50/15's.

I eventually narrowed my choices down to Continental, Toyo or Dunlop

Decided to go with the Dunlop Sport SP01 purely because they're as close to original as you're likely to get these days. Even though the tread pattern's not the same as the original D40, you've still got the original manufacturer tyre fitted. Could get them for about £75-80 per corner