Understood, I think I am going to stick with this carburetor for the 1969 Firebird. I have 2 of them and will compare/log the specs on each and report back when I have those. Once I have the tools to get those measurements it will be much easier to determine what if anything was modified.
Eyeballing the two they seem fairly identical and the jets were the same. Airhorn, body, and base are all correct on both. I just need to see if I can fix the baseplate for my spare or find an alternate that will work. My plan is to build one for 93 octane, and the other for E85. I have 2 17057274 QJ as well , but the linkage and vents are different enough I'll use them on my 1981 with a 400 instead.