Paul Grant sales used parts as does Will Tillery, info is in DiscoMike's signature to contact both of these guys. The outer A-Pillar that is cracked at the top goes for about $125-$150 new I think. The plastic front corner gutter finisher is a piece you can get used reasonable from Paul or Will, they may have the outer A-Pillar as well. You will want to make sure you see the attaching points and method for that A-pillar when you take it off in order to put the new one back on with care. I have not replaced mine, but I understand if not done correctly it can break. The top windshield seal is another part you may need, you probably want to go new with that due to aging rubber parts are not all that great. Rovers North, Atlantic British or Rovafarm may have that new. They may have the other parts new as well if you want to go that route on the plastic as aging plastic can be brittle as well. All three vendors noted can be found with a Google search.
That is a ugly mess you have there.