66 carbs are junk,,you want 68 or newer...or a 71 800cfm..
the real trick set up is a 1000cfm thermoquad..its the sh!t..it ran circles around holley and Qjets back in the day, they fell out of favor because parts ran out..now you can buy new ones again...it bolts right on the qjet intake
ive paid as little as 50 for an intake,,a couple years ago i bought one for 150..it sat around and i sold it because i didnt think i would ever use it..then when i needed one, none avail but $500+, i thought i got a good deal..and still do