Have to agree, Cliff Ruggles is the man you want to talk to about your Q-Jet. Cliff's High Performance, Mt. Vernon, Ohio.
His kits include the tubes. He knows which carbs need the larger ones (emmissions related). Not cheap, but absolutely the most complete "kit" available. He and I disagree on floats, though. I prefer brass, as "Qaudra-Flood" is an earned nickname, based on "heavy" fiber floats. Many a rebuilt Q-Jet has been scrapped because it still would "flood" after the rebuild, when a new float would have cured it. Brass floats don't get "heavy" unless they leak. Borg Warner, NAPA and many others still offer brass for most carb numbers.
Though more "Pontiac-related", his book is among the most comprehensive studies of Q-Jet. Cliff is a Pontiac guy, and is responsible for the carbs on some of the quickest NHRA SS Pontiacs including the Angeles car (9.0s '68 Firebird, C/SS/A). Virtually everything applies to all Q-Jets, regardless of original brand. SA Designs is the publisher.