Carb Differences

So i have my 66 barracuda with the 273. I have been working to get it running better since i got it and have replaced the holley 2bbl "truck"? carb with a 1850 that is running pretty good. I got some 67 hipo valve covers and the 273 commando air cleaner so to use the cleaner i had to get a different base plate to try and fit it tho it is only a 9" plate. This weekend it picked up a 67 carter from the 67 hipo so it should be a perfect fit but its only a500 cfm.