There is no "one answer fits all questions".
If you plan to use the truck as a tow vehicle to tow a heavy trailer, then a square-bore genuine Carter AFB or Holley. The larger primaries on the square-bore aid in lower RPM torque for towing.
On the other hand, if the truck will only occasionally be used for towing a light trailer, or not being used for towing; then an applicable spread-bore (Q-Jet or Carter TQ) might be the cat's meow.
Most Q-jets CAN be modified, however, it is generally much easier, and often cheaper in the long run to start with a carb DESIGNED for the engine in question, rather than taking something off a very different application and doing the necessary modifications. Check the second line in my signature block.
Supply the stamped identification numbers of your Q-Jets, and your utilization desires for the truck, and you will get more specific answers.
And you will notice I ignored the other question as I cannot in good conscience recommend this item for other than a doorstop.
Jon.
