Which Brake Booster?

Ooops! I just saw your country flag! Yes postage can be brutal back and forth. If you can find a later working booster, that will still work if you use your brackets between the firewall and booster. Even B and and most C bodies will work. You might also try a booster from a late model FWD car. I think there's a member here who is using a booster and master cylinder from a late model Plymouth Breeze on his Dart.