Just so you know...my 73 280 has vacuum lines that are still in good working order, and not brittle. (even the ones in the trunk)
And, comne to think of it, all the time I spent so far pulling of and refitting the ^&%&% $olex carb., I have not come across a brittle line in the engine compartment either.
The actuators, however, are a different story.
-Larry