I could be wrong, but I think the dual bolt pattern is so you can use either a Quadrajet, or a spreadbore Holley on that intake.
You might be able to put the squarebore carb on that spreadbore intake, but I'm pretty sure you'll have to tune for strange fuel delivery problems. The adapter plate would work, but check your hood clearance.
What engine, cam, heads, tranny, rear end? What vehicle is this in?
chip
