If your doing a lot of towing, its hard to beat the 440 in a gas motor, but its got to be built for towing, not a race car, or a 4x4 car crusher.

Until the efi Magnums, the best gas mileage I ever got out of a truck was with a big block truck. Once the efi Magnum came out, gas mileage was a different story all together. But the Magnum didn't do much better than an average LA 360 when you hooked the trailer behind it, and that was 2-3 mpg less then a big block with the same load, and the big block had more power pulling the load up hills then either small block.

That all said, a Magnum motor with a carb is stupid thinking, it won't perform to the level of the efi in either power or mileage. If your doing the Magnum, step up to the efi as well. I've heard the story about how you can't fix them if they break down on the road. Hey, reality check, unless you can fix your broke down carbed truck on the road, most shops are not equipped to fix a carbed truck either! Then chasing down parts could be a nightmare as well. Then you also have to consider the cost of converting the magnum motor to carbs and standard ignition systems. Its time to learn modern tech, step into the new century, its been here for 17 years already and the last carbs were factory installed 11 years before that.

It would also be wrong not to point out all the stuff that needs to be changed when you put any small block where a big block was. Gene