First, I don't have a wonderful '72 V12 XKE; BUT, if your ZS's are shot, I think you mean the gasoline has dried in them and the rubber parts have turned to glue. Just rebuild them with rebuild kits. There is a carburetor cleaner that is so strong it comes in two liquid layers (the sealer floating on top of the cleaner) and the container has a basket suitable for dipping and soaking carb parts. Take the carb apart and soak them until the gum and other deposits can be cleaned and rebuild the carbs. Other wise, you will need matching SU carbs with the correct needles and jets. A real tuners challenge. Just my $0.02.