Hi there sabre great to have you back on line and out of jail (bet the food is much better back home ) Please dont start building any trailers or corvettes for a day or two Lol Ray n Joy.
Thanks MY081. Nice to be out. Not much chance of starting anything new, no driving for 6 weeks or heaving lifting for 3 months.
Sabre - you are correct - but the two hot air valves need vac from the port in the base of the carburetor.
Manual for '78 shows the pickup at front left carb base. On the Excalibur (305) hose goes from the carb port, thru a temp valve mounted under the air cleaner, then to a "Y" connector which feeds to both diverter valves.
stuclark - Note that these are rarely connected in Australia. The air preheater is primarily for sub zero operation, but if disconnected it is necessary to block the port in the base to prevent vac leaks.
The picture you originally posted shows the flex couplings and original ducts are missing. This is also common as they wear, are a pain to reconnect and crowd the engine bay; however these are more important in Aust as they attempt to get cool air into the carby rather than preheated air from behind the radiator. There's a huge debate over whether the restriction provided by the ducting or the increased air inlet temperature loses more power, but all agree cool air into the aircleaner is a good idea. I'm sure you'll get lots of varied opinions on this.
Good luck!