The Carter AFB is a square-bore, the AVS has a spread bore, but not exactly the same as the Q-Jet. I have seen pix (in Santucci?) of a GM factory 250/292 iron intake for a 4Bbl Q-Jet. Also the old Pontiac Sprint OHC 250 L6 was sometimes set up for a Q-Jet. Maybe in Latin America, where alcohol is the fuel of choice, bigger CFM needs are encountered?

I/I #4101
'71 GMC Jimmy 350, sm465, np205,3.73 posi.
'68 C/10 Stepside 292 (.030 over) Offy Intake, 500 CFM AFB,Clif headers, sm465, 3.73 posi.
'67 K/10 454 project.
'72 K/5 rolling frame project.