273 advise needed

LOL, There is no intelligence in AI. the 3858s AFB is for a 1965, 413 cu in big block, in a C-Body. Not even close for a 273. You should be able to get it running if it is in decent shape though. It is jetted too rich and has no velocity valve in the secondary. Additionally the correct AFB carbs for the CAP automatic transmission 273's are 1966 4122s and 1967 4305s.

I do not believe the Edelbrock carbs will fit without a spacer since the secondary bores will not open fully because of the small bores in the OEM intake. the air cleaner will not fit either.

I don't like Holley carbs and they will need an adapter as well as a different air cleaner and MOPAR throttle adapter.
Yes, I had to have the secondary bores in the intake machined larger and I bought a cheap air cleaner just for the base so I could use the OEM Charger 273 air cleaner.