I would stick with the quadrajet.....you'll get better mileage on those primaries than you would any other carb....that holley is not to small but... both sets of barrels open progressively which will shoot a big hole in any mileage....

Don't go over 5psi on fuel pressure or you'll be heading for trouble....6 is pushing it....

If you want an extra kick from that 4 barrel...remove the steel rod from the secondary side from the vaccum actuator ( the rod from the back choke door ) as you are standing over the hood it's on the back left top and hooks to the secondary air valve from the choke pull off...

You will then have to re-adjust the air-horn opening rate to what you like (not hard) this mod will wake up that tired Q-jet...

Just besure the air-horn doesn't open too fast or it will create a bog when you punch it....